I was able to fix the virus definition debacle McAfee that is hosing a bunch of people.

It turns out, that they put in a bad signature that quarantines your SVCHOST.exe which could cause your explorer to crash. Good times, right?

So, the fix is pretty easy:

1 Restart into safe mode with networking

2 open a Command window. If your explorer isn't started, hit CTRL - ALT - DEL  and hit Task Manager. Hit File, run. CMD.EXE and enter.

3) type DEL C:\Program Files\Common Files\McAfee\Engine\avvscan.dat

4 type cd c:\windows\system32\dllcache

5 type copy SvcHost.exe ..\

6 Restart your PC. You are good to go!

NOTE: If you need help getting into safe mode, click here. Or, pull the power cord during the boot after seeing the LOGO. Then boot normal, which will give the boot mode option screen. Pick Safe Mode with Networking (Without networking, you can’t use your cached domain account).
Happy Coding!