Hello, I tried to install 2Gb of RAM (DDR500) to my computer and then booted up and now I cannot Log-in to my XP Pro SP2. It loads to the password screen and thats as far as it goes. I log-in and it immediately logs back out and thats it. I tried loading in safe mode by holding F8 and that did not work it only prompts me to load from different drives or CD-ROM; NO safe mode option. My BIOS only registers 3Gb of memory not 4GB like it should. I know this RAM is compatible because I was running only 2Gb of exact same RAM for a while and now tried adding 2GB more. I also know that the MAX Ram for MoBo is 4GB so that should not be an issue either. If this was sold as new but might have been used RAM could this mean it is dead/corrupt, causing errors or have a virus? I even removed all and booted each one by itself and checked BIOS to see if it registered and they all checked out individually but when slots are fully populated it only registers 3Gb. I tried booting with the ASUS MoBo CD in drive with no results. i even tried to boot using the Windows Xp pro CD and ran a clean install of windows (did not format) had a few SP2 errors (because I don't have an SP2 disk???) but overall it finished then on reboot it froze up. I rebooted and same thing; it will not go past the log-in screen where it prompts for my password. I know its not a password issue because it would tell me if I put in an incorrect PW. Any Ideas? this is an urgent matter, please help.