I was able to reproduce this on three (!!) different systems! I tried a clean new library: no change.
System 1:
Media Center
Install Path: C:\Program Files (x86)\!Multimedia\JRiver Media Center 17\
Interface Plugins: Inactivity Plugin (running), TiVo Server (disabled, not running), Sleep Timer (running)
JRMark: never run
Library: 61917 files, 22,0 MB in library, 801 MB in thumbnails
Resources: 113 MB memory, 939 handles
Version: 17.0.103.0 registered
Batteries
Microsoft ACPI-konforme Kontrollmethodenakku (driver 6.1.7600.16385)
Microsoft Composite Battery (driver 6.1.7600.16385)
Microsoft-Netzteil (driver 6.1.7600.16385)
Biometric Devices
TouchChip Fingerprint Coprocessor (WBF advanced mode) (driver 1.5.0.289)
Computer
ACPI x64-based PC (driver 6.1.7600.16385)
Disk drives
Generic External USB Device (driver 6.1.7600.16385)
SAMSUNG HD103UJ (driver 6.1.7600.16385)
ST9500420AS (driver 6.1.7600.16385)
Display adapters
Intel(R) HD Graphics Family (driver 8.15.10.2538)
NVIDIA NVS 4200M (driver 8.17.12.7593)
DVD/CD-ROM drives
HL-DT-ST DVDRAM GT33N (driver 6.1.7601.17514)
MagicISO Virtual DVD-ROM0000 (driver 6.1.7601.17514)
Human Interface Devices
HID-konformes Benutzersteuergerät (driver 6.1.7600.16385)
HID-konformes Benutzersteuergerät (driver 6.1.7600.16385)
USB-Eingabegerät (driver 6.1.7601.17514)
USB-Eingabegerät (driver 6.1.7601.17514)
USB-Eingabegerät (driver 6.1.7601.17514)
USB-Eingabegerät (driver 6.1.7601.17514)
IDE ATA/ATAPI controllers
Intel(R) Mobile Express Chipset SATA AHCI Controller (driver 10.1.0.1008)
Imaging devices
Integrated Camera (driver 1.1.0.1147)
Keyboards
HID-Tastatur (driver 6.1.7601.17514)
Standardtastatur (PS/2) (driver 6.1.7601.17514)
Memory
Free Physical Memory: 4,2 GB
Total Memory: 7,9 GB
Mice and other pointing devices
HID-konforme Maus (driver 6.1.7600.16385)
ThinkPad UltraNav Pointing Device (driver 15.3.34.0)
Modems
ThinkPad Modem Adapter (driver 7.80.5.0)
Monitors
Nicht-PnP-Monitor (Standard) (driver 6.1.7600.16385)
SyncMaster T260HD(Digital) (driver 3.0.0.0)
ThinkPad Display 1920x1080 (driver 4.36.0.0)
Network adapters
Cisco AnyConnect VPN Virtual Miniport Adapter for Windows x64 (driver 2.4.173.0)
Intel(R) 82579LM Gigabit Network Connection (driver 11.15.16.0)
Intel(R) Centrino(R) Ultimate-N 6300 AGN (driver 14.3.0.6)
Microsoft-Adapter für Miniports virtueller WiFis (driver 6.1.7600.16385)
Operating System
Microsoft Windows 7 64-bit
Processors
Intel(R) Core(TM) i7-2620M CPU @ 2.70GHz (driver 6.1.7600.16385)
Intel(R) Core(TM) i7-2620M CPU @ 2.70GHz (driver 6.1.7600.16385)
Intel(R) Core(TM) i7-2620M CPU @ 2.70GHz (driver 6.1.7600.16385)
Intel(R) Core(TM) i7-2620M CPU @ 2.70GHz (driver 6.1.7600.16385)
Security Devices
Trusted Platform Module 1.2 (driver 6.1.7600.16385)
SM Driver
SM bios service (driver 6.1.1019.0)
SM bus service (driver 6.5.1018.0)
Smart card readers
Integrated Smart Card Reader (driver 4.1.0.1)
Sound, video and game controllers
ASUS Xonar U1 Audio Device (driver 7.12.8.2157)
Conexant 20672 SmartAudio HD (driver 8.32.23.2)
NVIDIA High Definition Audio (driver 1.2.23.3)
Storage controllers
MagicISO SCSI Host Controller (driver 2.7.106.0)
Storage volume shadow copies
Standard-Volumeschattenkopie (driver 6.1.7600.16385)
Standard-Volumeschattenkopie (driver 6.1.7600.16385)
Standard-Volumeschattenkopie (driver 6.1.7600.16385)
System devices
2nd generation Intel(R) Core(TM) processor family DRAM Controller - 0104 (driver 9.2.0.1011)
2nd generation Intel(R) Core(TM) processor family PCI Express Controller - 0101 (driver 9.2.0.1011)
ACPI-Deckel (driver 6.1.7601.17514)
ACPI-Energiezustandknopf (driver 6.1.7601.17514)
ACPI-Schalter (driver 6.1.7601.17514)
ACPI-Thermozone (driver 6.1.7601.17514)
Busenumerator für Verbundgeräte (driver 6.1.7601.17514)
DMA-Controller (driver 6.1.7601.17514)
Eingebetteter, Microsoft ACPI-konformer Controller (driver 6.1.7601.17514)
Enumerator-Treiber für Microsoft Virtual Drive (driver 6.1.7601.17514)
Erweiterter E/A-Bus (driver 6.1.7601.17514)
Hauptplatinenressourcen (driver 6.1.7601.17514)
High Definition Audio-Controller (driver 6.1.7601.17514)
High Definition Audio-Controller (driver 6.1.7601.17514)
Hochpräzisionsereigniszeitgeber (driver 6.1.7601.17514)
Intel(R) 6 Series/C200 Series Chipset Family PCI Express Root Port 1 - 1C10 (driver 9.2.0.1016)
Intel(R) 6 Series/C200 Series Chipset Family PCI Express Root Port 2 - 1C12 (driver 9.2.0.1016)
Intel(R) 6 Series/C200 Series Chipset Family PCI Express Root Port 4 - 1C16 (driver 9.2.0.1016)
Intel(R) 6 Series/C200 Series Chipset Family PCI Express Root Port 5 - 1C18 (driver 9.2.0.1016)
Intel(R) 6 Series/C200 Series Chipset Family SMBus Controller - 1C22 (driver 9.2.0.1011)
Intel(R) Management Engine Interface (driver 7.0.0.1144)
Intel(R) QM67 Express Chipset Family LPC Interface Controller - 1C4F (driver 9.2.0.1016)
IPBusEnum Root Enumerator (driver 6.1.7601.17514)
Microsoft ACPI-konformes System (driver 6.1.7601.17514)
Microsoft Windows-Verwaltungsschnittstelle für ACPI (driver 6.1.7601.17514)
Microsoft Windows-Verwaltungsschnittstelle für ACPI (driver 6.1.7601.17514)
Microsoft-Systemverwaltungs-BIOS-Treiber (driver 6.1.7601.17514)
Numerischer Coprozessor (driver 6.1.7601.17514)
PCI-Bus (driver 6.1.7601.17514)
PnP-Softwaregeräte-Enumerator (driver 6.1.7601.17514)
Programmierbarer Interruptcontroller (driver 6.1.7601.17514)
Remote Desktop Device Redirector Bus (driver 6.1.7600.16385)
System CMOS/Echtzeituhr (driver 6.1.7601.17514)
Systemlautsprecher (driver 6.1.7601.17514)
Systemplatine (driver 6.1.7601.17514)
Systemzeitgeber (driver 6.1.7601.17514)
Terminalserver-Maustreiber (driver 6.1.7601.17514)
Terminalserver-Tastaturtreiber (driver 6.1.7601.17514)
ThinkPad PM Device (driver 1.64.0.0)
Treiber für Datei-als-Volume (driver 6.1.7600.16385)
UMBus-Stamm-Busenumerator (driver 6.1.7601.17514)
UMBusenumerator (driver 6.1.7601.17514)
UMBusenumerator (driver 6.1.7601.17514)
Virtual PC-Hostbustreiber (driver 6.1.7601.17514)
Volume-Verwaltung (driver 6.1.7601.17514)
Universal Serial Bus controllers
Generic USB Hub (driver 6.1.7601.17586)
Generic USB Hub (driver 6.1.7601.17586)
Generic USB Hub (driver 6.1.7601.17586)
Generic USB Hub (driver 6.1.7601.17586)
Intel(R) 6 Series/C200 Series Chipset Family USB Enhanced Host Controller - 1C2D (driver 9.2.0.1021)
Intel(R) 6 Series/C200 Series Chipset Family USB Enhanced Host Controller - 1C26 (driver 9.2.0.1021)
USB-Massenspeichergerät (driver 6.1.7601.17577)
USB-Root-Hub (driver 6.1.7601.17586)
USB-Root-Hub (driver 6.1.7601.17586)
USB-Verbundgerät (driver 6.1.7601.17586)
USB-Verbundgerät (driver 6.1.7601.17586)
USB-Verbundgerät (driver 6.1.7601.17586)
USB-Virtualisierung
USB-Virtualisierungsconnectortreiber (driver 6.1.7601.17514)
System 2:
Media Center 17.0.99.0 registered -- C:\Program Files\!Multimedia\J River Media Center 17\
Workstation 6.1 Service Pack 1 (Build 7601)
Intel Pentium M 1346 MHz MMX / Memory: Total - 1047 MB, Free - 502 MB
Internet Explorer: 9.0.8112.16421 / ComCtl32.dll: 5.82.7601 / Shlwapi.dll: 6.1.7601 / Shell32.dll: 6.1.7601 / wnaspi32.dll: N/A
Ripping / No CD drives found.
Digital playback: Yes / Get cover art: Yes / Calc replay gain: Yes / Copy volume: 100
Eject after ripping: Yes / Play sound after ripping: No
Burning / No burners found.
Test mode: No / Eject after writing: No / Direct decoding: No / Write CD-Text: No
Use playback settings: No /
Portable Device Info
Removed devices: Multi Flash Reader (E:),G:\,F:\,HTC TD2,EXILIM,CANON_DC,NIKON D40,FREECOM 4GB
Interface Plugins:
TiVo Server
Sleep Timer (Active)
System 3:
Media Center 17.0.46.0 registered -- C:\Program Files\!Multimedia\JRiver Media Center 17\
6.1 Service Pack 1 (Build 7601)
Intel Core 2 2147 MHz MMX / Memory: Total - 2095 MB, Free - 880 MB
Internet Explorer: 9.0.8112.16421 / ComCtl32.dll: 5.82.7601 / Shlwapi.dll: 6.1.7601 / Shell32.dll: 6.1.7601 / wnaspi32.dll: N/A
Ripping / Drive Y: HL-DT-STDVDRAM GSA-H42L Mode:ModeSecure Type:Auto Speed:Max
Drive Z: SONY DVD-ROM DDU1615 Mode:ModeSecure Type:Auto Speed:Max
Digital playback: Yes / Get cover art: Yes / Calc replay gain: Yes / Copy volume: 100
Eject after ripping: Yes / Play sound after ripping: No
Burning / Drive Y: HL-DT-ST DVDRAM GSA-H42L Addr: 1:0:0 Speed:48 MaxSpeed:48 BurnProof:Yes
Test mode: No / Eject after writing: Yes / Direct decoding: No / Write CD-Text: Yes
Use playback settings: Yes /
Portable Device Info
Removed devices: CASIO DIGITAL_CAMERA (K:),CASIO DIGITAL_CAMERA (E:),CASIO DIGITAL_CAMERA (G:),EXILIM,G:\,HTC TD 2,W:\,HTC TD2,New Device (Q:),NIKON D40,X:\
Interface Plugins:
Inactivity Plugin
TiVo Server
Sleep Timer (Active)