Augh! I have exactly the same problem. I guess it's slightly good to hear that someone else is having the same one.
My symptoms are identical to what you're reporting. I've got a custom zt3000 w/ these details on the service tag:
Pavilion zt3000
p/n: DL812AV
512 MB of RAM, I think the 1.5 GHz processor.
I also assume that it's a problem with something critical like the motherboard. I've been searching the web a bit and did find this sale on eBay of a faulty motherboard from our model of computer. The seller reports the same basic symptoms and claims that it can be fixed by replacing a couple of display chips. I don't know if that would solve our problem or if we could even find these chips:
http://cgi.ebay.com/FAULTY-HP-Pavilion-ZT3000-Motherboard-Spares-Repair_W0QQitemZ6881700698QQcategoryZ51162QQssPageNameZWDVWQQrdZ1QQcmdZViewItem (eBay auction for faulty mobo)
So anyway, I'm trying to decide whether to have some place like Geek Squad fix it under some sort of flat rated deal, or trying to snag a motherboard on eBay for cheap and swapping it out myself. I've plenty of experience with PCs (assembling them myself, etc.), but basically none with notebooks.
What did you decide to do with yours?
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