some people forgot about something when removing virus..
-disabling system restore. that's why the virus can reincarnate
-safe mode . why it's called "SAFE"
-recovery disk. most AV provide their own recovery disk.just need to burn it

prevent>cure = Malwarebyte+MSE or AVIRA or AVG or KARSP etc

and please.. format as last option.. yes... unless you've infected with virut.yeah just format your pc

correct me if im wrong. thanks