I have had a problem for a little while, and I think I have narrowed it down to a problem with my Wireless driver.
At first it seemed completely random. Sometimes I could use my computer for hours without any problems, other times it would start breaking after just ten or fifteen minutes. The symptoms of the breakage are the following: The network stops working (Intel Wifi diagnostic tool passes all tests except the ping-test) and I can no longer load any web pages. The Wireless light turns off but the indicator in the system tray still indicates that a connection is active. When I try to open the configuration tool to disconnect/reconnect, it does not respond. If I run "ipconfig /all" from the command line, it does not show any interfaces.
Other, weirder symptoms seem to be related to the computer running out of resources. Trying to start an application might trigger a message from Explorer that says it doesn't know how to open files of that type, a lot of applications will complain about running out of memory (although the task manager says I have lots of memory available), some applications will say that files are corrupt. When I reboot, everything is fixed, and the "corrupt" files are working fine again, so it doesn't seem to be a hardware-related issue.
Now, the reason I think this is related to the Wireless driver is that it always happens when I'm downloading files at a high bandwidth. Typically it happens when I use Free Download Manager and get rates of 2 MB/s. I've used that download manager for a while before without any problems, and the issues do not disappear when I close it, so I don't think it's related to the application. I've also copied files at much higher rates without any problems, so I don't think the issue is with the disk drivers. The only thing I can think of that has changed with my setup recently is that I've upgraded my Internet connection and get higher transfer rates now than before. My shot in the dark is that the wireless driver is leaking some type of resource handle (I've been unable to figure out exactly what type, it does not hold an excess amount of USER or GDI objects according to Task Manager) and this is causing all sorts of random results.
I upgraded my Intel driver and software to the latest version today (version 126.96.36.199) but that did not make any difference unfortunately.
I'm hoping someone out there has had similar problems and maybe even some suggestions for a solution, because it's annoying as hell having to reboot my computer whenever I've downloaded something.