Please print out or copy this page to Notepad. Make sure to work through the fixes in the exact order it is mentioned below. If there's anything that you don't understand, ask your question(s) before proceeding with the fixes. You should 'not' have any open browsers when you are following the procedures below.
Restart your computer and boot into Safe Mode by hitting the F8 key repeatedly until a menu shows up (and choose Safe Mode from the list). In some systems, this may be the F5 key, so try that if F8 doesn't work. Make sure to close any open browsers. Run a scan in HijackThis. Check each of the following and hit 'Fix checked' (after checking them) if they still exist (make sure not to miss any):
O2 - BHO: (no name) - {77DDAA3C-7BD7-0EB4-1CC3-967EF812AFB4} - C:\WINDOWS\System32\cdmweb\yhmvxsgevn.dll
O4 - HKLM\..\Run: [KavSvc] C:\WINDOWS\System32\vzzauv.exe reg_run
Delete the following Files/Folders (delete folders if no filename is specified) according to their directory (if none, just do a search for them) and delete them if they exist:
C:\WINDOWS\System32\cdmweb\
C:\WINDOWS\SYSTEM32\mc-58-12-0000079.exe
C:\WINDOWS\SYSTEM32\pop2.exe
C:\WINDOWS\SYSTEM32\US4.0-3.exe
C:\WINDOWS\SYSTEM32\xjxxmo.exe
C:\WINDOWS\SYSTEM32\ysbinstall_1003032.exe
C:\WINDOWS\SYSTEM32\eliteewt32.exe
C:\WINDOWS\SYSTEM32\eliteoei32.exe
C:\WINDOWS\SYSTEM32\eliteuxx32.exe
C:\WINDOWS\ojkzmrcb.exe
C:\WINDOWS\rrtitoajhvp.exe
C:\WINDOWS\System32\vzzauv.exe
Restart and run a new HijackThis scan. Save the log file and post it here.