Alright, I own this old Laptop the HP pavillion ZD7000, that i mainly use to stream youtube videos on my Tv, and one day i put new thermal paste on and after that everything worked perfectly fine until about a month later. At FIRST I noticed the computer would restart when ever i connect my 1TB external HDD from seagate, and when playing movies and youtube videos after about 25 mins would give me a blue screen saying "begin dumb of physical memory'. I though this computer was full of junk and re-installed WINDOWS thinking it would fix the problems. I had gotten all the drivers and everything ran fine. The computer ran faster and quicker but the problem with the blue screen didn't disappear. I though it was the RAM (will list the specs at the end) so i inserted the Ubuntu CD version 9.10 and began a memory test, which my computer passed perfectly, and also the HD test. I have no idea what's going on and im starting to think that the CPU is overheating........ Is there a piece of software that could tell me what temperature my CPU is running at, and what temp is should be?

Specs:
HP pavillion ZD7000
3.00 GHz intel pentium 4 processor
512 MB of (i think DDR 1 not 100% sure but its 256 X2)
80GB HDD
Screen is bad and therefore im using it as a youtube TV. Test the memory again with this:
http://www.memtest86.com/download.html

Download the "ISO image for creating bootable CD (Windows - zip)", burn it to a CD then boot the computer from that CD. Run the test and let it run for multiple passes (this will take hours, best to do it overnight). Errors won't always come on the first pass, sometimes they'll show up on the second, third, or later passes. If you get any errors, remove the RAM and make sure the contacts aren't corroded or dirty and the slot is clean, put it back in and run the test a second night. If the errors persist, the RAM is bad.

Run it with Ubuntu for a while and actively use it for a while (surf the web, watch videos, play music, whatever) and see if it gets an error or lucks up.

What did you use to diagnose the hard drive? If you didn't use the hard drive manufacturer's tool, download it and try it. They should be able to tell you better than anyone whether the drive is malfunctioning or not.

As for heat, download Speedfan:
http://www.almico.com/sfdownload.php

It runs in Windows and will tell you the CPU and other temps.For the bluescreen error messages : Download BlueScreenView (in Zip file) then unzip(extract by right clicking) and run Bluescreenview.
Go to Edit -Select All, File and Saved Selected Item. Create a name for the report, just make sure it is a .txt extension file like Report.txt. Copy/Paste ALL the created report on your next post.
alright here are the results from speed fan:

at start-up the system ran at: 54C (degrees)
then it began to rise from 55, 56, 59, 60 and stayed at 60 Degrees which watching youtube and simpsons movies online
the most it went was 64C and only taking up 30% CPU.
I used Ubuntu 9.10 and when i went to 'try ubuntu without doing changes to computer' it started to boot and after the boot screen i got a flashing purple screen, same thing when i clicked install ubuntu.
Im going to try the memory test and will try the newest version of ubuntu or at least 10.04. the MEMTEST is the exact same one thats on the ubuntu 9.10 CD and it passed the testQuote from: comda on September 09, 2011, 05:45:57 PM

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Specs:
HP pavillion ZD7000
3.00 GHz intel pentium 4 processor
512 MB of (i think DDR 1 not 100% sure but its 256 X2)
80GB HDD
Screen is bad and therefore im using it as a youtube TV.

i used the HD diagnostics given on the ubuntu 9.10 linux CD and the result was that it was alright. Im not quite sure where to get a HP diagnostics tool,

...are you sure it could be the drive? ...