Very bizzare. However, this is very unlikely to be malware.
Most of the information I've come across relating to this problem points to a failing video card. Does the machine in question have a dedicated graphics card or strictly use onboard video?
Additionally, let's check out the RAM.
Test the memory (RAM).
- Run memtest86+ for a minimum of 24 hours for a reliable result if no errors are reported beforehand.
- Memory needs to be tested outside of Windows, so memtest86+ is run from a bootable CD.
To make a bootable CD with memtest86+:
- Download the Pre-Compiled Bootable ISO (.zip) from near the bottom of the memtest86+ page.
OR ... use the following direct download link: Download - Pre-Compiled Bootable ISO (.zip)
- Extract the downloaded zip file:
- Right-click on the zip file and choose Extract all. (Windows XP ... other Windows versions may have different wording.)
The contents of the zip file (the .ISO image file) will be extracted to a folder in the same location as your zip file.
- Burn the .ISO image to CD: If you do not already have a suitable burning program for writing .ISO images to disc ...
- Download and install ImgBurn.
- Ensure that you UN-check the box agreeing to install the Ask toolbar during the installation.
- Place a new (blank) CD disc in the drive tray.
- Choose Write image file to disc.
- Under Source, click on the Browse button: Navigate to and select the .ISO file that you wish to burn.
- Place a check-mark in the box beside Verify.
- When the CD has been burned and verified as successful, it will be bootable.
Boot from the newly created CD.
- You may need to configure BIOS or the Boot Menu to boot first from the CD.
- memtest86+ will begin running automatically: You need do nothing else at this time.
- Allow memtest86+ to run un-interrupted.
- See the screenshots in this informative link: Diagnose with Memtest86+
- There MUST be NO errors whatsoever:
- If you see an error, stop the test.
- Then proceed to test each stick of RAM separately to sort the good from the bad.
- A minimum test for some confidence in the result, should be 7 full passes (each "pass" is a series of different types of tests), with NO errors.
- Allow memtest86+ to run for 24 hours for maximum confidence in the test result.
- memtest86+ will continue running until you stop it:
- Press the Escape key to reboot the computer, removing the memtest86+ CD.
Reference: Overclockers forums Memtest86+ Guide/How To's