Why does my compaq presario 5000 shut down with no prompt.

THis is from the HP tech chat thing, and it seems to be working. I did method 2 and browsed to the file:
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1. Click Start 2. Click Shutdown 3. The "Shut Down Windows" dialog box will be displayed 4. Select "Shut Down" from the me 5.
Start the system again. 6. When the Red Compaq logo appears press F8 repeatedly until prompted with the "Windows Startup
Menu" 7. Select option 6 (Safemode Command Prompt) by pressing the down arrow key until Safe Mode Command Prompt is
highlighted 8. Press Enter 9. At the C:\ prompt type D: and press Enter 10.At the D:\ prompt type CD CPQS and press Enter
11.At the D:\CPQS prompt type XQR press Enter
Method 2:
1. Click Start 2. Click Run 3. In the "Open" box type C:\CPQS\QUICKSR\FRESTORE.EXE Performing these steps should resolve this
issue.

Once try to Re-Install your Operating System and Just after Installing your OS just once Mo niter your CPU usage in Task Manager if it is Simply raising to 80% to 100% then it is a issue of over heating

Just go to the HP website under support and follow the prompts. They will list everything possible about that computer including the manuals.

Is it shuting down? Or just instantly going off.

If it is shutting down, adjust the power settings.

• Control Panel
• Power Options
• Make sure the scheme you want is selected. For a desktop it should be Home/Office or Always on.
• Make sure that System Standby and Hibernate (if available) are set to the length you want.

if you can view your desktop and use the menus, go to start/all programs/accessories/system tools/system restore, if you had enabled this option earlier then you can restore the system to an earlier known date when you system worked.
else you can try installing winXP again, try the option to "Update" when the install option comes on.
else start PC, before the WinXp screen comes on press F8 key, use the Safe Mode to start PC, if you can see everything then shut down and restart in normal mode.

your OS is damaged.. try installing a new one.

Visit driversguide.com, register yourself(its free) and finally visit this link:
http://members.driverguide.com/index.php?action=dosearch&qm0=Compaq+Presario+5000+PC&qa5=1&qa6=236&qa7=All+Windows&dp=3&sm=h&jmd=and&fzz=d&si=0714a172c4fc2aef5b5a2106375cb1db&st=1240205618&gqm0=Compaq+Presario+5000+PC+BIOS+Motherboard
and get your drivers.......sodeep

You first find a Windows installation disk valid for the licence sticker on computer, then download drivers from HP website.
Here driver page for Presario 5000 series :
Compaq Presario 5000 Desktop PC series - Download drivers

Here is a link which supplys all needed internal parts for you specific computer...

http://www.impactcomputers.com/compaq-presario-5500-desktop-parts-internal-parts-and-assemblies.html

what email program are you using?