This virus might be a google redirect trojan and it is not easy to clean, however, these are the first steps to take in trying to delete this nasty win32 virus.

go to start menu, then run, now type in MSCONFIG, go to startup tab and look for a long string of command that has random letters and sometimes numbers, disable that line and save.

Download Malwarebytes, update malwarebytes then do a full system scan. if any virus is found, it will delete it.

Now download spybot, do an update and a full scan, delete any melware or spyware it finds.

You surly must have a virus protection software, if not, download Microsoft Security Essentials, its free, update the app then a full scan.

These steps above should fix and delete the Trojan.win32.Generic.pak!cobra.Engine virus

Here are other virus trojans that are smiler to the one above and can be cleaned the same way.

Trojan.Win32.Generic!BT: Trojan
Trojan-Spy.Win32.Zbot.gen: Trojan
Exploit.PDF-JS.Gen (v): Exploit
Trojan.Win32.Generic!SB.0: Trojan
INF.Autorun (v): Trojan
Trojan.Win32.Hiloti.gen.d (v): Trojan
Trojan.Win32.Generic.pak!cobra: Trojan
Trojan.Win32.Adware: Adware (General)
MyWebSearch Toolbar: Potentially Unwanted Program
Trojan.Win32.Malware: Trojan