Ok, remember what I said about the possibilty of MSConfig causing memory leaks, if used to disable services and processes. Well, that might be the issue. This is what I would do, first open MSConfig, and retick everything you unticked. Then reboot. Once you do that, do the following. Make sure you follow each step by the letter, or you may not fix the problem.
This behavior may occur if one of the following conditions is true:
One or more of the random access memory (RAM) modules that are installed on your computer are faulty.
The RAM configuration is incompatible with Windows XP.
To troubleshoot this behavior, follow these steps:
1. Remove some of the memory modules that are installed on the computer. Leave at least the RAM that is required for the computer to start and run Windows XP.
The recommended RAM to run Windows XP is (at least) 256 megabytes (MB) I recommened 512MB. The minimum is 128 MB, and the maximum is 4 gigabytes.
For example, if two 256-MB memory modules are installed on your computer, remove one of the memory modules.
2. Restart your computer, and then run the Setup program:
a. Insert the Windows XP Setup CD-ROM in the CD-ROM drive, start the computer, and then click OK to select the first option screen to install a copy of Windows XP.
b. Click Accept, and then follow the instructions on the screen to complete the Windows XP installation.
3. If you again receive the error message that is mentioned in the "Symptoms" section, go to step 4.
4. Remove a different memory module, or install the RAM in a different memory slot.
5. Restart your computer, and then rerun Setup.
You may have to restart your computer several times to identify the specific memory modules that are not working correctly.
Hopefully this will fix your problem. So far, all the info I found points to ram (memory) issues.