A wierd problem.(Probably virus or hardware problem)

In a friend's computer I saw this wierd problem.
It is an ATI board.(1 IDE port , & SATA support, so probably 945,could be D101).

Now there is some software ATI Catalyst control Centre, which handles d onboard 128MB graphix card.
Now when the computer starts ,it shows an error that CLI.exe could not be started due to some problem.

What's wierd is I installed Windows on another partition & it shows same error right from d beginning.

I wanted to install TATA Indicom dialer.Now it gets installed but when I try to connect, as soon as "verifying username & password " appears , the computer restarts.The dialer is working on another comp wid Intel 845.

Now ,
.1) It could be virus prob but can't risk formatting whole disk & losing all data for nothing.
.2) Could be hardware issue of dialer with board, but why CLI.exe thing is not working wid new installation of Windows ??

Probably other specs won't matter , all OSs used r Windows XP.
Please help.........

Do u tried any antivirus??????

I did .
But as I told u I wanted to install TATA dialer, Well there never was any internet connection on that comp, so d anti virus hadn't been updated for 6 months.
Can't rely on that.