System: Windows 7 Professional 64bit. 8GB RAM, Intel i5-2400 CPU, +300GB free on the hard drive. AVG Internet Security 2012 (enabled & disabled, with firewall enabled and disabled - no effect for either). This computer is less than a year old.
Network: This problem is occurring on a single computer on a network with multiple computers. The router is a Motorola Netopia 3347-02 (DSL Modem/Wireless Router combined). The computer is plugged in directly to the modem, other computers are using the wireless successfully. The router has been reset. The only thing odd about the connection between the router and computer is that it is configured to allow RDP through, so it is assigned a static IP by the router and port forwarding is enabled for port 3389. Also, though I doubt it matters, a second wireless router is active behind this router providing a second network that some computers in the area use without issues.
Details: All downloads initiated on this specific computer eventually fail, this includes streaming from youtube, specialized downloads (itunes), downloads from websites, FTP downloads, etc. Failure occurs with all browsers, but in chrome this is the process it takes: 1) Download begins normally, 2) At some point between (observed) 7MBs and 229MBs the download stops progressing (at this point, if watching chrome's task manager, you can see the network activity for the downloading tab drop to 0kps), 3) for some time the download sits there still attempting to complete, but will eventually display "123,049,871/0 B, Interrupted" (where the number is whatever it actually got to).
The file I am using to test this is a very large .zip file located on a server I control, but the problem seems to occur on any site. The amount downloaded is completely random, and seems to be more time-based than anything (if I start a download immediately after the last one fails, it tends to get further than the last one). Small files can get through for this reason, though they can fail as well. In a test where I simultaneously downloaded the same file via HTTP (chrome) and FTP (windows explorer), both downloads failed at the same instant, though explorer displayed "Connection timed out" several minutes before chrome finally showed the download as interrupted.
Other things I have tried based on advice given to people with similar/identical problems:
Setting my MTU to 1492 (as described here: http://blog.thecompwiz.com/2011/08/networking-issues.html)
Disabling write caching to the hard drive
storing the download on an external device
successfully transmitted +1GB file from one computer on the same network to this computer
disabling indexing in the folder the download was being stored in
disabling all security software
checked to make sure all drivers were up to date
read about 50 accounts with nearly exact descriptions of what I'm experiencing, none of which had a solution given
Running Processes:
Image Name PID Session Name Session# Mem Usage
========================= ======== ================ =========== ============
System Idle Process 0 Services 0 24 K
System 4 Services 0 104,836 K
smss.exe 332 Services 0 1,276 K
csrss.exe 764 Services 0 5,060 K
wininit.exe 820 Services 0 4,748 K
csrss.exe 844 Console 1 23,764 K
services.exe 876 Services 0 11,856 K
lsass.exe 892 Services 0 14,420 K
lsm.exe 900 Services 0 7,820 K
winlogon.exe 944 Console 1 7,716 K
svchost.exe 428 Services 0 12,744 K
svchost.exe 796 Services 0 12,240 K
svchost.exe 1036 Services 0 22,372 K
svchost.exe 1084 Services 0 174,132 K
svchost.exe 1112 Services 0 56,144 K
svchost.exe 1288 Services 0 18,640 K
svchost.exe 1404 Services 0 29,616 K
spoolsv.exe 1576 Services 0 25,924 K
svchost.exe 1616 Services 0 12,788 K
AppleMobileDeviceService. 1728 Services 0 9,796 K
avgwdsvc.exe 1820 Services 0 8,268 K
mDNSResponder.exe 1844 Services 0 5,832 K
w3dbsmgr.exe 1108 Services 0 43,760 K
QBCFMonitorService.exe 1336 Services 0 16,408 K
svchost.exe 2404 Services 0 28,240 K
taskhost.exe 3020 Console 1 12,372 K
dwm.exe 2280 Console 1 5,968 K
explorer.exe 2964 Console 1 152,476 K
WUDFHost.exe 3316 Services 0 6,740 K
svchost.exe 3408 Services 0 5,556 K
RAVCpl64.exe 3684 Console 1 13,864 K
igfxtray.exe 3700 Console 1 7,804 K
hkcmd.exe 3772 Console 1 7,868 K
igfxpers.exe 3788 Console 1 10,940 K
sidebar.exe 3836 Console 1 84,400 K
chrome.exe 3964 Console 1 19,640 K
pptd40nt.exe 4068 Console 1 5,156 K
acrotray.exe 3908 Console 1 14,676 K
avgtray.exe 3872 Console 1 9,508 K
jusched.exe 4076 Console 1 4,412 K
iTunesHelper.exe 1532 Console 1 87,308 K
SearchIndexer.exe 3492 Services 0 36,948 K
iPodService.exe 4136 Services 0 7,944 K
BrccMCtl.exe 4276 Console 1 18,132 K
splwow64.exe 4380 Console 1 32,600 K
qbupdate.exe 4836 Console 1 24,236 K
svchost.exe 4288 Services 0 20,700 K
wmpnetwk.exe 3112 Services 0 9,516 K
FNPLicensingService.exe 5248 Services 0 5,852 K
QBW32.EXE 5508 Console 1 127,068 K
QBDBMgrN.exe 5600 Services 0 42,252 K
EXCEL.EXE 2512 Console 1 99,100 K
LMS.exe 3188 Services 0 5,616 K
UNS.exe 1600 Services 0 7,308 K
axlbridge.exe 5260 Console 1 5,132 K
chrome.exe 5888 Console 1 200,336 K
chrome.exe 3536 Console 1 26,076 K
chrome.exe 1952 Console 1 20,168 K
chrome.exe 4596 Console 1 24,696 K
chrome.exe 4292 Console 1 48,096 K
chrome.exe 2796 Console 1 23,520 K
Acrobat.exe 1240 Console 1 87,252 K
123w.exe 4892 Console 1 22,728 K
calc.exe 1700 Console 1 12,636 K
chrome.exe 1328 Console 1 28,888 K
chrome.exe 3696 Console 1 47,012 K
rundll32.exe 6320 Console 1 7,104 K
chrome.exe 4928 Console 1 44,248 K
AVGIDSAgent.exe 260 Services 0 12,940 K
avgfws.exe 6052 Services 0 26,912 K
avgnsa.exe 5064 Services 0 2,496 K
avgrsa.exe 3088 Services 0 2,200 K
avgcsrva.exe 2596 Services 0 380 K
avgcsrva.exe 6948 Services 0 408 K
StikyNot.exe 452 Console 1 14,772 K
chrome.exe 4580 Console 1 28,200 K
chrome.exe 4016 Console 1 57,756 K
svchost.exe 7140 Services 0 4,500 K
chrome.exe 6264 Console 1 56,824 K
chrome.exe 7008 Console 1 56,896 K
chrome.exe 2224 Console 1 38,032 K
taskhost.exe 612 Console 1 7,228 K
chrome.exe 6000 Console 1 10,928 K
chrome.exe 2568 Console 1 43,052 K
chrome.exe 272 Console 1 75,988 K
chrome.exe 7328 Console 1 53,240 K
PaprPort.exe 7976 Console 1 137,152 K
pplinks.exe 7500 Console 1 14,052 K
ppscanmg.exe 5744 Console 1 18,996 K
taskeng.exe 7388 Console 1 6,308 K
SearchProtocolHost.exe 8024 Services 0 8,804 K
SearchFilterHost.exe 7232 Services 0 7,848 K
chrome.exe 8016 Console 1 37,440 K
cmd.exe 7692 Console 1 3,096 K
conhost.exe 7516 Console 1 5,872 K
tasklist.exe 8160 Console 1 5,772 K
WmiPrvSE.exe 7684 Services 0 6,400 K
Any help with this would be greatly appreciated, I've been beating my head against a wall over this all day. This computer serves dual purpose as the main company document server and the Owner's work computer, it's fairly important it be fully functional and I cannot figure this out.