60C isnt bad. I know my card can get up to 70C under full load. Those are the final drivers and there are no Beta Drivers. I would head over to nvidia's site and see what they say. Cause there is nothing explaining why this would be happening from a Windows standpoint.
The error you are receiving is a driver failure. Since you have the latest driver it is either a bug with the driver that needs to be fixed, or a bug in Win7 RC that has been addressed for the final.
If it is the latter of those, then there is nothing that can be done but waiting for Win7 to get released in Oct and installing the final version.