Try lowering the intensity a bit. I can solo mine in guiminer scrypt using reaper at intensity 18 but in cgminer scrypt I can't go over about 15 without just getting continual hw errors like that. I'm using 3 7950s.
This is in Cgminer with a 7970. Stays like that indefinitely. Best share is always 0 whereas if I am mining a SHA256 coin, best share varies.
