Are you saying that the usual disable is now busted?
I have an HP pavilion d4100Y running XP SP2 (purchased in 2005). The "Updates for HP Agent" started running almost constantly a year or so ago (can't exactly remember when)despite the fact I first set the udates to "Never" run, then when that did not work I uninstalled HP Update. When I end the task from the Task Window, the program disappears from the list but comes back again at some point without my starting the Updates program.
The problem is that it consumes the lion share of the CPU (like 80-90%), preventing anything else from running. All other programs freeze when the Updates start. Very frustrating. Cannot get an answer from HP tech support who sent me to the HP support webiste where I spent countless hours trying to find any help -- I discovered that other people have this problem, but the "solutions" were not solutions.