9800 gt- monitor flashes on and off on certain web pages

I bought a new custom AMD dual core with a 460 watt power supply. I wanted to use some hardware left from a pavilion M9200t media center that turned out to be a piece of junk. I am trying to use a GeForce 9800GT which is originaly a vista era card that seemed to work ok at first. After experimenting a few days and not being used to windows 7, I began to notice the monitor would flash black and then back on continously all the while I was on certain web pages, especially ones that are more security sensative. Monitor is a new flat screen HP 2310M that has been tested on another PC and works flawlessly on a DVI-D cable. Most web pages work fine but when I am on a problem page the only way I can stop the flashing is to set the resolution for the screen way down before I go there. I've updated the nvidia card with the latest drivers, tried different browsers such as Firefox. I guess my question is do I need to get a newer card for the windows 7 32 bit OS I am running, or is there a patch of some kind?--------------Thanks I advance--LG