WOW!!!!! post all your computers specs(every bit of hardware) and if you can download anything
BIG"B's Linked Online Security FOR XP
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SOFTWARE
Top Four Security Downloads (you must have them)

• FIRE WALL DOWNLOAD HERE
• AV DOWNLOAD HERE
• SPY WARE REMOVER DOWNLOAD HERE
• ANTI-TROJAN DOWNLOAD HERE

Note: All downloads above are worthless without updates

Hi,
As u have installed windows twice thrice..it may creates memory troubles or may be registries also responsible for this... for improving speed..u can defrag hard drive, delete unneeded files,remove useless programs,remove temporary files, delete remnants of
the uninstalled programs...
u can also do disk clean up..!!

As for cleaning & optimizing.. u can try Advanced System Optimizer..It has lot of utility and has best optimizers with it..!!
Registry Cleaner
Registry Optimizer
System Cleaner
Disk Optimizer

they all can fix the problems that i stated above..!!

It will definitely help in improving system speed...try it..!!

http://www.tucows.com/preview/284138...stem+optimizer

I think there is a problem in the RAM. You have to increase the RAM. Otherwise there is a problem of the virus so use the Genuine Antivirus and scan the computer. Yet the problem is not solved out than format your computer otherwise contact to your hardware engineer.