switched MC's browser to Chromium, same issue, here are the logs (store and reader only):
Media Center; Version: 16.0.75; Types: 16127
0000000: 6112: General: Starting logging: Date: 4/30/2011 7:46 PM
0000000: 6112: General: Log Reset: Logging reset
0004150: 6112: General: CMCResourceHelper::GetIsModalPopupShowing: Main window disabled
0013822: 6112: Reader: CInternetReader::Open: Start
0013822: 6112: Reader: CInternetReader::Open: Opening
https://rover.jriver.com/cgi-bin/Lassie/SOAP.cgi0013822: 4588: Reader: CInternetReader::Thread: Start
0013822: 4588: Reader: CInternetReader::Connect: Start
0013822: 4588: Reader: CInternetReader::Connect: Finish (0 ms)
0013822: 4588: Reader: CInternetReader::DownloadFromHTTPURL: Start
0033821: 6112: Reader: CInternetReader::Open: ConnectToURL failed, timed out (20000 ms), URL=https://rover.jriver.com/cgi-bin/Lassie/SOAP.cgi
0033821: 6112: Reader: CInternetReader::Close: Start
0038829: 6112: Reader: CInternetReader::Close: Finish (5008 ms)
0038829: 6112: Reader: CInternetReader::Open: Finish (25007 ms)
0038829: 6112: Store: ECommJRiverTier1Medianet::JRiverLogin: Login Elapsed ms: 25007.237
0080575: 6112: Reader: CInternetReader::Open: Start
0080575: 6112: Reader: CInternetReader::Open: Opening
https://rover.jriver.com/cgi-bin/Lassie/SOAP.cgi0080575: 6572: Reader: CInternetReader::Thread: Start
0080575: 6572: Reader: CInternetReader::Connect: Start
0080575: 6572: Reader: CInternetReader::Connect: Finish (0 ms)
0080575: 6572: Reader: CInternetReader::DownloadFromHTTPURL: Start
0100574: 6112: Reader: CInternetReader::Open: ConnectToURL failed, timed out (20000 ms), URL=https://rover.jriver.com/cgi-bin/Lassie/SOAP.cgi
0100574: 6112: Reader: CInternetReader::Close: Start
0105582: 6112: Reader: CInternetReader::Close: Finish (5008 ms)
0105582: 6112: Reader: CInternetReader::Open: Finish (25007 ms)
0361455: 6112: Store: OnBeforeNavigate: Start
0361455: 6112: Store: OnBeforeNavigate: Navigate URL - C:\Users\JEFF\AppData\Roaming\J River\Media Center 16\Stores\Performer Media Center\Webpages\current.html
0361455: 6112: Store: OnBeforeNavigate: Redirect URL -
0361455: 6112: Store: OnBeforeNavigate: Finish (0 ms)
0361455: 6112: Store: OnBeforeNavigate: Start
0361455: 6112: Store: OnBeforeNavigate: Navigate URL - C:\Users\JEFF\AppData\Roaming\J River\Media Center 16\Stores\Performer Media Center\Webpages\current.html
0361455: 6112: Store: OnBeforeNavigate: Redirect URL -
0361455: 6112: Store: OnBeforeNavigate: Finish (0 ms)
0361533: 6112: Store: OnBeforeNavigate: Start
0361533: 6112: Store: OnBeforeNavigate: Navigate URL - C:\Users\JEFF\AppData\Roaming\J River\Media Center 16\Stores\Performer Media Center\Webpages\current.html
0361533: 6112: Store: OnBeforeNavigate: Redirect URL -
0361533: 6112: Store: OnBeforeNavigate: Finish (0 ms)
0000468: 6248: Reader: CInternetReader::Open: Start
0000468: 6248: Reader: CInternetReader::Open: Opening
http://www.musicex.com/cgi-bin/redirects/MC/v16/redirect.pl?type=dependency&prodname=Media Center&version=16.0.75&dependency_name=chromium&dependency_version=1
0000499: 6880: Reader: CInternetReader::Thread: Start
0000499: 6880: Reader: CInternetReader::Connect: Start
0000499: 6880: Reader: CInternetReader::Connect: Finish (0 ms)
0000499: 6880: Reader: CInternetReader::DownloadFromHTTPURL: Start
0020498: 6248: Reader: CInternetReader::Open: ConnectToURL failed, timed out (20000 ms), URL=http://www.musicex.com/cgi-bin/redirects/MC/v16/redirect.pl?type=dependency&prodname=Media Center&version=16.0.75&dependency_name=chromium&dependency_version=1
0020498: 6248: Reader: CInternetReader::Close: Start
0025522: 6248: Reader: CInternetReader::Close: Finish (5024 ms)
0025522: 6248: Reader: CInternetReader::Open: Finish (25054 ms)
0025756: 6248: Store: JRMediaNetSoap::JRMediaNetSoap: Start
0025756: 6248: Store: JRMediaNetSoap::JRMediaNetSoap: Finish (0 ms)
0025756: 6248: Store: JRMediaNetStore::JRMediaNetStore: Start
0025756: 6248: Store: JRMediaNetStore::JRMediaNetStore: Finish (0 ms)
0000078: 6804: Store: CMNMetering::CMNMetering: Start
0000078: 6804: Store: CMNMetering::CMNMetering: Finish (0 ms)
0000515: 6804: Store: CMNMetering::CMNMetering: Start
0000515: 6804: Store: CMNMetering::CMNMetering: Finish (0 ms)
0000515: 6804: Store: CMNMetering::DoMetering: Start
0000515: 6804: Store: CMNMetering::DoMetering: Finish (0 ms)
0046707: 6248: Reader: CInternetReader::Open: Start
0046707: 6380: Reader: CInternetReader::Open: Start
0046707: 6248: Reader: CInternetReader::Open: Opening
http://prod-services-configuration.musicnet.com0046707: 6380: Reader: CInternetReader::Open: Opening
http://prod-services-configuration.musicnet.com0046707: 5884: Reader: CInternetReader::Thread: Start
0046707: 5884: Reader: CInternetReader::Connect: Start
0046707: 6520: Reader: CInternetReader::Thread: Start
0046707: 6520: Reader: CInternetReader::Connect: Start
0046707: 5884: Reader: CInternetReader::Connect: Finish (0 ms)
0046707: 6520: Reader: CInternetReader::Connect: Finish (0 ms)
0046707: 5884: Reader: CInternetReader::DownloadFromHTTPURL: Start
0046707: 6520: Reader: CInternetReader::DownloadFromHTTPURL: Start
0066706: 6248: Reader: CInternetReader::Open: ConnectToURL failed, timed out (20000 ms), URL=http://prod-services-configuration.musicnet.com
0066706: 6380: Reader: CInternetReader::Open: ConnectToURL failed, timed out (20000 ms), URL=http://prod-services-configuration.musicnet.com
0066706: 6248: Reader: CInternetReader::Close: Start
0066706: 6380: Reader: CInternetReader::Close: Start
0071729: 6380: Reader: CInternetReader::Close: Finish (5023 ms)
0071729: 6248: Reader: CInternetReader::Close: Finish (5023 ms)
0071729: 6248: Reader: CInternetReader::Open: Finish (25022 ms)
0071729: 6380: Reader: CInternetReader::Open: Finish (25022 ms)
0071729: 6248: Store: JRMediaNetSoap::GetWebServiceURL: failed for name=Discovery, with response =
0071729: 6380: Store: JRMediaNetSoap::GetWebServiceURL: failed for name=Fulfillment, with response =
0071729: 6248: Store: JRMediaNetStore::Load: GetWebServiceURLs returned FALSE, commerce=https://rover.jriver.com/cgi-bin/JRCommerce/SOAP.cgi, discovery=, fulfillment=
0071729: 6248: Reader: CInternetReader::Open: Start
0071729: 6248: Reader: CInternetReader::Open: Opening
http://www.musicex.com/cgi-bin/redirects/MC/v16/redirect.pl?type=StoreCachedData&prodname=Media Center&version=16.0.75&service=Performer Media Center
0071729: 6356: Reader: CInternetReader::Thread: Start
0071729: 6356: Reader: CInternetReader::Connect: Start
0071729: 6356: Reader: CInternetReader::Connect: Finish (0 ms)
0071729: 6356: Reader: CInternetReader::DownloadFromHTTPURL: Start
0091728: 6248: Reader: CInternetReader::Open: ConnectToURL failed, timed out (20000 ms), URL=http://www.musicex.com/cgi-bin/redirects/MC/v16/redirect.pl?type=StoreCachedData&prodname=Media Center&version=16.0.75&service=Performer Media Center
0091728: 6248: Reader: CInternetReader::Close: Start
0096736: 6248: Reader: CInternetReader::Close: Finish (5008 ms)
0096736: 6248: Reader: CInternetReader::Open: Finish (25007 ms)
0096736: 6248: Store: JRMediaNetStore::GetCommerce: ecommtype=2
0096736: 6924: Store: JRMediaNetStoreUpdateStoreLibraryThread::Thread: Start
0096752: 6924: Reader: CInternetReader::Open: Start
0096752: 6924: Reader: CInternetReader::Open: Opening
http://files.jriver.com/dependencies/mnlibrary/v3/version.dat0096752: 4372: Reader: CInternetReader::Thread: Start
0096752: 4372: Reader: CInternetReader::Connect: Start
0096752: 4372: Reader: CInternetReader::Connect: Finish (0 ms)
0096752: 4372: Reader: CInternetReader::DownloadFromHTTPURL: Start
0096752: 6248: Reader: CInternetReader::Open: Start
0096752: 6248: Reader: CInternetReader::Open: Opening
http://www.musicex.com/cgi-bin/redirects/MC/v16/redirect.pl?type=dependency&prodname=Media Center&version=16.0.75&dependency_name=chromium&dependency_version=1
0096752: 6004: Reader: CInternetReader::Thread: Start
0096752: 6004: Reader: CInternetReader::Connect: Start
0096752: 6004: Reader: CInternetReader::Connect: Finish (0 ms)
0096752: 6004: Reader: CInternetReader::DownloadFromHTTPURL: Start
0116751: 6924: Reader: CInternetReader::Open: ConnectToURL failed, timed out (20000 ms), URL=http://files.jriver.com/dependencies/mnlibrary/v3/version.dat
0116751: 6924: Reader: CInternetReader::Close: Start
0116751: 6248: Reader: CInternetReader::Open: ConnectToURL failed, timed out (20000 ms), URL=http://www.musicex.com/cgi-bin/redirects/MC/v16/redirect.pl?type=dependency&prodname=Media Center&version=16.0.75&dependency_name=chromium&dependency_version=1
0116751: 6248: Reader: CInternetReader::Close: Start
0121759: 6924: Reader: CInternetReader::Close: Finish (5008 ms)
0121759: 6924: Reader: CInternetReader::Open: Finish (25007 ms)
0121759: 6924: Store: JRMediaNetStoreUpdateStoreLibraryThread::Thread: Local version: ; Server version:
0121759: 6924: Store: JRMediaNetStoreUpdateStoreLibraryThread::Thread: Finish (25023 ms)
0121759: 6248: Reader: CInternetReader::Close: Finish (5008 ms)
0121759: 6248: Reader: CInternetReader::Open: Finish (25007 ms)
0122164: 6248: Store: OnBeforeNavigate: Start
0122164: 6248: Store: OnBeforeNavigate: Navigate URL - C:\Users\JEFF\AppData\Roaming\J River\Media Center 16\Stores\Performer Media Center\Webpages\current.html
0122164: 6248: Store: OnBeforeNavigate: Redirect URL -
0122164: 6248: Store: OnBeforeNavigate: Finish (0 ms)