Ugh. Suddenly Mac's are eerily reminiscent of PC's.
Believe me, you don't experience that kind of trouble in modern Macs.
Unfortunately, the computer did not come with the 8.6 CD. So I suppose I'm stuck then, because I can no longer get into OS 9 at all, extensions or none.
Try starting the Mac while pressing Command + Option + P + R, and wait until you hear the startup chime for the second time before releasing the keys. That will reset the PRAM in the machine, and that might get it back working.