You have had a virus attack, luckily your antivirus has already removed some of it from your PC. One trace remains in the registry which will try to load it on start up.
Ok, do the following step and get rid of it.
Open Run , type regedit and press enter
Go to
HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows NT \ CurrentVersion \ Winlogon
and check for the key Shell, the value of this must be Explorer.exe . if you can see some other after that like Explorer.exe C:\PROGRA~1\MYWEBS~11\bar\1.bin... , then remove the second file from the value, you want it to be only Explorer.exe
Ok, then check for the key Userinit. the value must be C:\WINDOWS\system32\userinit.exe, (including the comma) . If you find something else there , then delete it.
then restart your system .
You may need to delete the browsers anddownload fresh copies on another computer and burn them to a CD. You should also run a complete virus scan.
Good Luck