humm not much to say other then what's been said.. One thing I can think of is if the heatsink uses a box type fan.. If it is in the correct position.. see if u can get into bios I go to your hardwaremonitor in the bios and make sure the cpu isn't getting overheated...
here is a link to your manual A7V133 in pdf form.. it does have a clear CMOS list on board (edit page 59)
ftp://ftp.asus.com/pub/asus/mb/socka...a7v133-102.pdf
also somethign u might think about.. this is a pre XP board.. and if I rememrb the specs right on the XP chip it is suppose to run at a lower voltage I'll have to check up on that and make sure.. if so.. maybe the mother board is giving the cpu to much power?
(edit) FRom what I can find it is running at 1.75v .. which is normal voltage for even a athy.. but mine runs at 1.83..
this can be found here.. section 7.9
http://www.amd.com/us-en/assets/cont...docs/24309.pdf