Well both cards are GeForce 7950 GT's on an ASUS P5Q Delux MB. They were both working fine (I think) and had been in the system for over a year. Recently, I started getting random lockups that got so bad, I couldn't even boot in safe mode. Decided to reload Vista, switching from 64 bit to 32 (tired of looking for drivers that weren't written yet for certain apps I've got). Now I notice the lack of the SLI config page. I really hadn't looked at it since install way back when, so I don't really know exactly when it may have changed for sure. I've pulled and reinstalled the cards to be sure they're seated rite.
Asus P5Q Delux
8 GB Mem OCZ Platinum
Intel Quad Core Q9300 Yorkfield 2.5 GHz
Thermaltake Purepower 600 W
eVGA GeForce 7800 GT 256MB X 2
BTW, I've still got the lockups, altho not nearly as frequent. Seems to occur when I'm messing around with config files or driver files as in device manager. (sic)