Basically what this error message is telling you is that the program tried to access some information stored in the system memory, but it couldn't read it.
Now, RAM sticks are notoriously difficult to detect faults with. What I would suggest is that you try going
here and downloading Memtest86.
The instructions are a little complex. If you need guidance, the easiest method is to do the following:
1. Download this file:
http://www.memtest86.com/memt32.zip
2. Extract the files into a folder. The name of it doesn't matter. Just have all the files there in the same place.
3. Doubleclick Install, and have a floppydisk ready in the drive.
4. Hopefully everything should go fine, and when this is done the floppy disk will no longer be readable by Windows. This is normal.
5. Reboot the system fully and have the floppy disk in the drive when you do so. The RAM testing should automatically begin. Press Escape at any time to exit the test and have the computer reboot.
Note that this is a TEST, and does not fix anything. Errors reported by this test should be noted for future reference.
You may also wish to defragment your harddrive. This can be done by rightclicking the drive in your My Computer folder, selecting Properties, going to the Tools tab, and starting from there.