I replaced my nvidia 7800gt with a ATI x1900xt. I updated the drivers to cat 6.5 and it is very unstable. Sometimes it will reboot and start over saying I don't have any ati software installed. I'm running a 1920x1200 res. I've been thinking I have some virus of some sort since my puter has been acting up before I installed the new card. Any suggestions would be great. Thanks