BSOD when running chdisk on Dimension 4600

Contrary to many on here, I have had few (no major)problems with my Dell Dimension 4600. It is a sweet machine and I hope to be able to use it for some time in the future (although it is almost 4 years old). Anyway, the problem: every time I run chdisk it runs through all 5 stages but when it starts to give the summary it goes to the BSOD. Some of the error codes are OX0000007E, OXC0000005,OXF8A2E51D. This happens every time I run chdisk. The first time it scared me, but now I am used to it, but still something must be wrong for this to happen. Any ideas?