Sounds like something is messing with your computer. If it happens even in DOS, it'd be apparent that your CPU has gone loco.
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Computer specs:
CPU: Intel Celeron M 450MHz
RAM: 1GB DDR2 100MHz
Storage: 4GB SSD + 8GB SDHC
Monitor: 7" LCD WVGA 800x480
OS: Windows XP Professional w/ SP3
Road warrior operation duration: 4h30m! (extendable to 6h30m!) 