I'm not sure why re-installing drivers would fix the problem for a couple weeks...

I have a similar issue with my computer, though much less serious. A few times now (over the last few years) the sound has just stopped working. The first time I checked the speakers, all the sound settings, tried known working speakers, etc. A clean re-instal of the drivers fixes the problem, though Windows, DirectX, etc all say they were installed properly before and working fine.


I'd check out the SVCHOST.exe file; the first google hit I got says it may be a legitimate Windows process, but it could be malware depending on which directory it is running from.