Windows XP SP3 Running Very Slow at Times

Hello,

I'm running WIndowx XP Pro - SP3 on a Dell Dimension Desktop Computer - lately it seems that the computer is running in slow motion, but only sometimes. Starting programs takes a while, right clicking causes a delay - its like the computer has to take time to think about what I'm doing before it lets me do it - it seems that once I start doing something then I'm ok, but getting there is like walking through wet concrete.

I've run a complete scan using Norton Internet Security (with latest updates) which came up clean. I've run a complete scan using the latest MalWareBytes, which also came up clean.

I'm looking for the next step of advice. Any help would be greatly appreciated.

Thanks!!

via Bleeping Computer Last 20 Posts http://www.bleepingcomputer.com/forums/t/512957/windows-xp-sp3-running-very-slow-at-times/