Open your win.ini file in Notepad.
Look for a line like
run=fhdhksf.exe (it'll be a name consisting of random letters)
delete that line.
Now search for the file that appeared on the line and delete it.
Download and use AVG6 Free Edition click here instead of Command.
You will need to replace WSOCK32.DLL (might be why you internet connection is knackered) Put your Windows CD in the CD ROM drive and go to Start, Run, type
sfc and hit enter.
then Extract WSOCK32.DLL and put it in windows/system folder.