I have a Gateway 3310 PC with Windows XP SP2 at 2.66 Ghz and a Intel Celeron processor. The computer originally had 2 sticks of Samsung 256MB DDR RAM PC3200 CL3. I recently went out and bought 2 sticks of Centon 512MB DDR RAM that is running currently at 333 MHz I do believe. At first everything was fine, then a day later Windows started acting funny so I rebooted the computer and it was then that I noticed the slowdown. It took longer for Windows to boot. And for the first few boots whenever I clicked on anything Windows would just freeze and I had to reboot the computer. Then it was okay but it is still running slower than it should. One strange thing that is also happening is when I go to shut down the menu comes up as normal asking if I want to shut down, restart or stand by. But for some reason I cannot choose the stand by mode I can only shut down or restart.