This may seem obvious, but have you tried reinstalling the software?

I don't know why this is, and it hurts my head to even think such a thing is possible, but I've found that Microsoft stuff installs with different errors on multiple install trys on the same machine. I used to have to install NT4 on a compaq work station 3 to 5 times to get a stable (hah!) install. An install of NT4 was usually good for about a year... Euuu... I finally convinced the company to upgrade all the machines to Windows98, prior to winders 2000 coming out.

I've also seen older CDs that have oxidized and bits of the code become unusable, you may want to try installing from another CD.