My comp is jerking

[bossuwe]

This jerkings happen even if im idle... I dunno what happens to my comp and it starts only 2 days ago.. (sound works perfectly)
Every 3 2 secs , i'll jerk//lag spike
I'm aware that my comp has a virus but i'm unable to remove it even when in Safe Mode but i don't think this is the problem.
What is a possible cause to this problem?

System spec:
Pentium 4 2.4 GHZ
768MB Ram
ATI 9800 PRO (5.9 Catalyst driver)

 

[misterv]

WOOOOAAAAHHHHH it has a virus? If you're having trouble removing it, find a very good friend w/ antivirus (or another one of your PCs) and stick the harddrive from the infected computer on it. Don't worry...just make sure it's the slave drive so your infected OS won't load. Then have the guy run a virus scan on your drive and it should clean up the files. (make sure it's set to clean and not delete so it doesn't axe an important system file). Anyways, get rid of that first before bothering with anything else. (take a log of all the files that were infected so if one does get deleted you can copy that file again from said very good friends HD). I can't tell you the number of friends I've done that on and it worked perfectly (but beware I've definitely had a few that landed me rescuing all their important data files and reinstalling their system, and man that'll ruin your weekend...).

 

[spherrod]

Yep - I think your first priority would be to get rid of the virus. Do you know what virus it is?

 

[bossuwe]

Its Backdoor.Win32.Prorat.19