I have my agp voltage set at 1.6 for my 9600XT card this may be a bit high.
http://www.viaarena.com/default.aspx...=5&ArticleID=9
There is a artical on the loop error hope it helps, there is no one fix for this problem, it my personel oppinion that most of the time its related to a poor quality or under powerd psu