May be there is virus problem with your computer but don;t worry.
There may be also other reason. So First try to delete all temporary files and folders and also %temp%, prefetch, and after performing these try to run disk clean up utility which will increase in system performance.
But make sure that you are using one more heavy application or game on your computer but thereonly 512 MB of RAm I it will be better to you to increase in System Memory (RAM) will also increase system speed and performance.
Try the Best best of Luck
try to visit this site for live help ...
http://www.iyogi.co.uk
PRINCE
June 2009