Possible virus problem?

[Unisaw]

I'm visiting my mom and checking her computer to make sure automatic updates is turned on, etc...  She is running Windows XP and has AVG 9.0 as her security software.  When I tried to manually run a scan, the scan went through about 100,000 files before the computer shuts down and reboots.  It did this three times in a row.  In checking the scan log for AVG, I determined that her computer has not successfully completed a scan in over a year.  There is also a notification that the scan log has been repaired.

Could this be a virus that shuts down the computer when it is about to be discovered by AVG?  If so, how should I proceed?

Thanks in advance.

[lupinus]

Tried safe mode?

May also want to try a second security software.

Download and install malware bytes as well as avast. Update um and run um. I'd also give spybot a go.

I find AVG to be excellent, but it's pretty common to have one thing effected and another work like a charm. Had a bad one one time that took five different programs multiple scans each to get rid of. Each scan and program found various bits and pieces.

[lee n. field]

Tried safe mode?

+1 to that.

AVG in safe mode scans in a command line mode.

Also, download the AVG live CD (Google it), burn it to disk.  Boot from it, let it update, and scan with that.

[lupinus]

Left out superantispyware.

Despite the name it is a very good product, IMO. Spybot finds some things it misses, SAS finds some things spybot misses.

[Unisaw]

Many thanks.  Unfortunately, I had to leave before I got it fixed.