Guiminer and radeon 6870 goes from 300mhash to 300khash after 5 mins

[btcgolong]

Guiminer and radeon 6870 goes from 300mhash to 300khash after 5 mins. I have tried the latest ATI drivers...I'm running windows XP, and Guiminer. It does say non-stratum at the beginning and the video card is not hot. I've looked for a sleep setting, etc and found nothing.

Let me know if you need more info (I'm working on this problem right now). I've searched and searched, others have had this problem, but I could not find a clear fix.




Thanks