As a regular (say 15 days at least) procedure please do the following to keep your computer functioning smoothly.
Clean CDROM lens and FDD heads with head cleaning kits
Run Antivirus Software provided on the Motherboard
Software CD delivered with your system (check for your model with our installation engineer)
after loading latest updates to keep your computer protected against viruses.
Run Disk Cleanup to free wasted space on your Hard Disk drive.
Run Disk Defragmenter to speed up the Hard Disk Drive of your PC
Check for your display settings including monitor refresh rates.
Remove any Screen savers or freeware games which change system settings in any way.
Frequently Asked Questions gives you a better insight into the world of computers.