Flaky VXDs and DLLs in Windows 9x? Check This Out!

Kenn's
Tech
Notes

19981201: Flaky VXDs and DLLs in Windows 9x? Check This Out!

December/1998
Tech Note #1

Tip of the Month! John S recently had an experience we can all learn from. He had a system running Windows 95 that repeatedly was giving error messages pertaining to DLL and VXD files. There didn't seem to be any particular pattern to the messages, nor any particular program or file, but the messages were frequent and the system became almost unusable. Reinstalling the software and the operating system did not solve the problem, so John systematically started replacing hardware. After he had replaced virtually every component in the machine, including the motherboard and hard drive, the problem remained. Everything was freshly installed, all the hardware was new, and still he would get messages indicating this VXD or that DLL was missing or corrupt or could not be loaded or fatal exception or illegal operation or any of a number of Windows 95's charming error messages.

The answer? The power supply. We have seen systems where a student has flipped the power selector switch from 115V to 230V, and the system - if it powers up at all! - will behave very strangely. In this case, the power selector switch was set correctly, but the power supply could not supply adequate current to the installed hardware.

A computer power supply converts the standard 115V AC external power source to internal positive and negative 12 and 5 volt DC sources. If the installed hardware draws more current than the power supply can provide, the 5 V supply (for example) will be dragged down. Different chips have different logic thresholds, but to give an example: If a chip normally interprets 0 V to 1.2 V as a zero and 3.8 V to 5 V as a one, and the power supply voltage is being periodically dragged down to 3 V, every bit which is received by that chip when the supply is 3 V will be interpreted incorrectly at least half the time.

The results will be unpredictable.

Moral of the story: When you're troubleshooting a system on which Windows is giving more error messages than usual, remember to include the power supply in your list of suspects!

DISCLAIMER: This document is intended for the reference of computer support personnel within Winnipeg School Division No. 1. There is no warranty or liability if procedures recommended here have an adverse affect on any systems. Use them at your own risk. Any trademarks mentioned are the property of their owners, none of whom have certified any information provided here. Opinions expressed here are personal only and do not represent the policy of Winnipeg School Division No. 1 or any other organization anywhere.

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