How long does a virus take to mess with a computer ?

[Genesis]

I recently downloaded something into my computer, about 5 days ago and last night i was on facebook and everything started messing up. But everything else works fine (it's just facebook) So i asked someone and he said it was definitely a virus. I really need this laptop for college it has all my work and information saved in it Help !
Oh and it's a MacBook, I don't think it makes a difference but incase it does.

[iamoop]

To be honest? it starts doing things in the background of your computer almost immediately.

Did a quick check and found a site for MAC AV scanners that is free.
http://www.clamxav.com/

(It being a Macbook can absolutely make a difference in diagnosis. You may want to check into where your nearest genius bar is (MAC Support)

http://www.apple.com/support/

[Danny H]

untill you clean your pc, delet the source of the virus or .... clean your PC

[HAL9000]

The first objective should be to backup your data to DVD, cd-r or backup drive. Next search google for some anti-virus software compatible with the MAC and run the scans.

Don't have a MAC so can't really recommend an app or walk you through the process. Just run a virus scan, spyware scan and malware scan.

Virus impact depends on what triggers it and how it was designed to attack.