Damn Windows XP

My sister's Athlon XP computer running Windows XP kept resetting itself even before it could get to the startup screen with the Windows icon and the bar scrolling. When it asked me what mode I wanted to restart Windows in I chose safe mode. It turned out that Windows was resetting itself after the file mup.sys had been loaded.

My first thought was that this particular file was corrupted. However it seems that other people had the same thought on the internet but it turned out to be merely a symptom of the underlying problem. It seems that the problem is with the Extended System Configuration Data (ESCD).

The ESCD is part of the Basic Input/Output System (BIOS) and specifies the allocation of resources to devices. This gets modified when changes to the hardware are made. The problem is that this process does not always go smoothly and the ESCD can get corrupted.

In theory this should be rectified by entering BIOS setup and getting it to reset the configuration data. However despite repeatedly configuring the BIOS to reset the configuration data Windows kept resetting itself. However I remembered back to a forum post that described how disabling the quick Power On Self Test (POST) mode fixed the problem. This indeed fixed the problem and Windows finally booted up with no problems.

I am yet to find a full explanation for why disabling quick POST fixed the problem but perhaps a full POST triggers the ESCD to be reset cleanly. The problem seemed to have started when an additional mouse was plugged into the system which seems to be a common problem. Fortunately I was made aware of the underlying problem.