I have pinpointed the location a few times, but I have no idea about the reason.
July 30, 2010:
C:\>tracert jriver.com
Tracing route to jriver.com [204.75.156.15]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms lo1-3.co3.pa1.hki.fi.eunetip.net [62.142.44.1]
2 1 ms 1 ms 1 ms ge9-22.mx1.pa1.hki.fi.eunetip.net [195.197.57.82]
3 1 ms 1 ms <1 ms ae2.helpa-p2.fi.elisa.net [139.97.16.130]
4 1 ms 1 ms 1 ms ae11.helpa-p1.fi.elisa.net [139.97.21.78]
5 1 ms <1 ms <1 ms ae2.heltli-gw1.fi.elisa.net [139.97.6.246]
6 1 ms 1 ms 1 ms ae1-10.bbr2.hel1.fi.eunetip.net [213.192.191.49]
7 8 ms 7 ms 7 ms as0-0.bbr1.sto1.se.eunetip.net [213.192.191.210]
8 7 ms 7 ms 7 ms 213.242.110.169
9 22 ms 79 ms 21 ms ae-2-5.bar1.Copenhagen1.Level3.net [4.69.140.198]
10 34 ms 33 ms 34 ms ae-7-7.ebr1.Dusseldorf1.Level3.net [4.69.142.170]
11 37 ms 37 ms 37 ms ae-48-48.ebr2.Frankfurt1.Level3.net [4.69.143.178]
12 125 ms 125 ms 125 ms ae-43-43.ebr2.Washington1.Level3.net [4.69.137.58]
13 137 ms 126 ms 125 ms ae-62-62.csw1.Washington1.Level3.net [4.69.134.146]
14 125 ms 125 ms 125 ms ae-61-61.ebr1.Washington1.Level3.net [4.69.134.129]
15 139 ms 143 ms 143 ms ae-2-2.ebr3.Atlanta2.Level3.net [4.69.132.85]
16 160 ms 160 ms 160 ms ae-7.ebr3.Dallas1.Level3.net [4.69.134.21]
17 163 ms 161 ms 162 ms ae-61-68.ebr1.Dallas1.Level3.net [4.69.146.66]
18 182 ms 181 ms 182 ms ae-8-8.car1.Phoenix1.Level3.net [4.69.133.29]
19 185 ms 184 ms 184 ms TELESPECTRA.car1.Phoenix1.Level3.net [4.53.104.30]
20 * * * Request timed out.
21 185 ms 186 ms 186 ms 66-17-80-70.sparkplugbb.net [66.17.80.70]
22 185 ms 186 ms 186 ms 66-17-80-82.sparkplugbb.net [66.17.80.82]
23 185 ms 186 ms 185 ms 66-17-80-94.sparkplugbb.net [66.17.80.94]
24 187 ms 188 ms 188 ms ATR-65102.sparkplugbb.net [66.17.84.102]
25 * * * Request timed out.
26 * * * Request timed out.
27 * * * Request timed out.
28 * * * Request timed out.
29 * * * Request timed out.
30 * * * Request timed out.
Trace complete.
Jyly 27, 2010:
C:\>tracert jriver.com
Tracing route to jriver.com [204.75.156.15]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms lo1-3.co3.pa1.hki.fi.eunetip.net [62.142.44.1]
2 1 ms 1 ms 1 ms ge9-22.mx1.pa1.hki.fi.eunetip.net [195.197.57.82]
3 1 ms 1 ms <1 ms ae2.helpa-p2.fi.elisa.net [139.97.16.130]
4 1 ms 1 ms 1 ms ae0.esptnl-p1.fi.elisa.net [139.97.21.146]
5 <1 ms 1 ms 1 ms ae3.heltli-gw1.fi.elisa.net [139.97.21.161]
6 1 ms 1 ms <1 ms ae1-10.bbr2.hel1.fi.eunetip.net [213.192.191.49]
7 8 ms 8 ms 7 ms as0-0.bbr1.sto1.se.eunetip.net [213.192.191.210]
8 7 ms 7 ms 7 ms 213.242.110.169
9 22 ms 21 ms 21 ms ae-2-5.bar1.Copenhagen1.Level3.net [4.69.140.198]
10 34 ms 34 ms 33 ms ae-7-7.ebr1.Dusseldorf1.Level3.net [4.69.142.170]
11 37 ms 38 ms 37 ms ae-48-48.ebr2.Frankfurt1.Level3.net [4.69.143.178]
12 125 ms 125 ms 125 ms ae-43-43.ebr2.Washington1.Level3.net [4.69.137.58]
13 125 ms 125 ms 125 ms ae-62-62.csw1.Washington1.Level3.net [4.69.134.146]
14 124 ms 125 ms 125 ms ae-61-61.ebr1.Washington1.Level3.net [4.69.134.129]
15 143 ms 144 ms 144 ms ae-2-2.ebr3.Atlanta2.Level3.net [4.69.132.85]
16 172 ms 163 ms 162 ms ae-7.ebr3.Dallas1.Level3.net [4.69.134.21]
17 174 ms 162 ms 162 ms ae-61-68.ebr1.Dallas1.Level3.net [4.69.146.66]
18 182 ms 182 ms 182 ms ae-8-8.car1.Phoenix1.Level3.net [4.69.133.29]
19 184 ms 184 ms 184 ms TELESPECTRA.car1.Phoenix1.Level3.net [4.53.104.30]
20 * * * Request timed out.
21 186 ms 186 ms 186 ms 66-17-80-70.sparkplugbb.net [66.17.80.70]
22 186 ms 186 ms 186 ms 66-17-80-82.sparkplugbb.net [66.17.80.82]
23 185 ms 185 ms 185 ms 66-17-80-94.sparkplugbb.net [66.17.80.94]
24 188 ms 186 ms 186 ms ATR-65102.sparkplugbb.net [66.17.84.102]
25 * * * Request timed out.
26 * * * Request timed out.
27 * * * Request timed out.
28 * * * Request timed out.
29 * * * Request timed out.
30 * * * Request timed out.
Trace complete.
June 15, 2010:
C:\tracert jriver.com
Tracing route to jriver.com [204.75.156.15]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms lo1-3.co3.pa1.hki.fi.eunetip.net [62.142.44.1]
2 1 ms 1 ms 1 ms ge9-22.mx1.pa1.hki.fi.eunetip.net [195.197.57.82]
3 1 ms 1 ms 1 ms ae2.helpa-p2.fi.elisa.net [139.97.16.130]
4 1 ms 1 ms 1 ms ae0.esptnl-p1.fi.elisa.net [139.97.21.146]
5 1 ms 1 ms 1 ms ae3.heltli-gw1.fi.elisa.net [139.97.21.161]
6 1 ms 1 ms 1 ms ae1-10.bbr2.hel1.fi.eunetip.net [213.192.191.49]
7 7 ms 8 ms 8 ms as0-0.bbr1.sto1.se.eunetip.net [213.192.191.210]
8 8 ms 8 ms 7 ms 213.242.110.169
9 22 ms 22 ms 22 ms ae-2-5.bar1.Copenhagen1.Level3.net [4.69.140.198]
10 34 ms 34 ms 34 ms ae-7-7.ebr1.Dusseldorf1.Level3.net [4.69.142.170]
11 37 ms 38 ms 38 ms ae-47-47.ebr2.Frankfurt1.Level3.net [4.69.143.174]
12 128 ms 127 ms 128 ms ae-42-42.ebr2.Washington1.Level3.net [4.69.137.54]
13 141 ms 129 ms 141 ms ae-82-82.csw3.Washington1.Level3.net [4.69.134.154]
14 139 ms 128 ms 142 ms ae-81-81.ebr1.Washington1.Level3.net [4.69.134.137]
15 152 ms 144 ms 144 ms ae-2-2.ebr3.Atlanta2.Level3.net [4.69.132.85]
16 174 ms 162 ms 162 ms ae-7.ebr3.Dallas1.Level3.net [4.69.134.21]
17 167 ms 162 ms 162 ms ae-61-68.ebr1.Dallas1.Level3.net [4.69.146.66]
18 185 ms 185 ms 185 ms ae-8-8.car1.Phoenix1.Level3.net [4.69.133.29]
19 186 ms 186 ms 186 ms TELESPECTRA.car1.Phoenix1.Level3.net [4.53.104.30]
20 * * * Request timed out.
21 187 ms 187 ms 188 ms 66-17-80-70.sparkplugbb.net [66.17.80.70]
22 191 ms 189 ms 189 ms 66-17-80-82.sparkplugbb.net [66.17.80.82]
23 187 ms 188 ms 188 ms 66-17-80-94.sparkplugbb.net [66.17.80.94]
24 188 ms 188 ms 189 ms ATR-65102.sparkplugbb.net [66.17.84.102]
25 * * * Request timed out.
26 * * * Request timed out.
27 * * * Request timed out.
28 * * * Request timed out.
29 * * * Request timed out.
30 * * * Request timed out.
Trace complete.
May 24, 2010:
C:\tracert jriver.com
Tracing route to jriver.com [204.75.156.15]
over a maximum of 30 hops:
1 1 ms <1 ms <1 ms lo1-3.co3.pa1.hki.fi.eunetip.net [62.142.44.1]
2 1 ms 1 ms 1 ms ge9-22.mx1.pa1.hki.fi.eunetip.net [195.197.57.82]
3 <1 ms 1 ms 1 ms ae2.helpa-p2.fi.elisa.net [139.97.16.130]
4 1 ms 1 ms 1 ms ae0.esptnl-p1.fi.elisa.net [139.97.21.146]
5 1 ms 1 ms 1 ms ae3.heltli-gw1.fi.elisa.net [139.97.21.161]
6 1 ms <1 ms 1 ms ae1-10.bbr2.hel1.fi.eunetip.net [213.192.191.49]
7 8 ms 8 ms 8 ms as0-0.bbr1.sto1.se.eunetip.net [213.192.191.210]
8 8 ms 8 ms 8 ms 213.242.110.169
9 22 ms 22 ms 22 ms ae-2-5.bar1.Copenhagen1.Level3.net [4.69.140.198]
10 34 ms 34 ms 34 ms ae-7-7.ebr1.Dusseldorf1.Level3.net [4.69.142.170]
11 38 ms 37 ms 38 ms ae-47-47.ebr2.Frankfurt1.Level3.net [4.69.143.174]
12 127 ms 128 ms 127 ms ae-42-42.ebr2.Washington1.Level3.net [4.69.137.54]
13 130 ms 128 ms 128 ms ae-82-82.csw3.Washington1.Level3.net [4.69.134.154]
14 141 ms 129 ms 141 ms ae-81-81.ebr1.Washington1.Level3.net [4.69.134.137]
15 142 ms 144 ms 144 ms ae-2-2.ebr3.Atlanta2.Level3.net [4.69.132.85]
16 172 ms 162 ms 161 ms ae-7.ebr3.Dallas1.Level3.net [4.69.134.21]
17 162 ms 176 ms 163 ms ae-61-68.ebr1.Dallas1.Level3.net [4.69.146.66]
18 186 ms 186 ms 186 ms ae-8-8.car1.Phoenix1.Level3.net [4.69.133.29]
19 187 ms 186 ms 186 ms TELESPECTRA.car1.Phoenix1.Level3.net [4.53.104.3]
20 * * * Request timed out.
21 189 ms 191 ms 190 ms 66-17-80-70.sparkplugbb.net [66.17.80.70]
22 192 ms 192 ms 191 ms 66-17-80-82.sparkplugbb.net [66.17.80.82]
23 188 ms 188 ms 188 ms 66-17-80-94.sparkplugbb.net [66.17.80.94]
24 189 ms 203 ms 189 ms ATR-65102.sparkplugbb.net [66.17.84.102]
25 * * * Request timed out.
26 * * * Request timed out.
27 * * * Request timed out.
28 * * * Request timed out.
29 * * * Request timed out.
30 * * * Request timed out.
Trace complete.
After being unable to accces JRiver.com a few times in May, I started to check the connection with tracert and save the logs. I expected that the problem would be eventually fixed after you have informed the service provider (I assume that Bob has not moved to Arizona

), but apparently it still occurs from time to time.
EDIT
I converted the precise file creation times to US Central Daylight Time:
July 30, 05:05 AM
July 28, 08:23 AM
June 15, 05:11 AM
May 24, 08:14 AM
I have never seen the problem occur later during the day (in CDT time).