Uno Board device driver trouble

I can't get the Ardunio UNO board to play nice with a WIndows 7 64 bit OS on a dell optiplex 745. The device drive on the virtual COM3 port is unstable. I followed the troubleshooting steps on this forum and was still unsuccessful. I am really out of ideas at this point. Has anyone hit this wall and found a way forward?? Your opinion is appreciated.

Thanks!

The device drive on the virtual COM3 port is unstable.

"Unstable"? Is it like a weeble? Does it have trouble staying upright?