Did you start with 7 and went back to 6? If so, if you don't completely remove all the newer drivers some files will probably not get replaced when you install older versions. I can vaguely remember for me it where the WDM drivers I messed up on, but can't remember ecxactly what the symptoms where. I do remember that after I installed the original drivers from the CD, including WDM, the card worked fine again and the issues went away. Not guaranteeing anything, but it's worth a try.