|Go to Knoppix.com or Ubuntu.com|
Download the free ISO file for the Linux variant there. Save it to hard drive; burn that ISO file to a dvd.
Boot with that dvd. The laptop will boot and load up Linux - within RAM only. This will allow you to go on-line to:
Look for and run Housecall; it's a free on-line virus scanner utility.
Let it install the few files it will require to run.
Let it do a full scan; and clean out/fix anything it finds...
Also and while you're booted into "Knoppix or Ubuntu" copy "all" your data - your personal files etc. (only) - to optical media and verify (check) the disks will play (read) properly on at least one other system. This to be sure your data is now safely duplicated off the laptop drive.
Then reboot laptop without the DVD and see if system is any better?