Error mounting Linux ext2fs drive

[Damon Butler]

I recompiled my kernel, including the "options EXT2FS" option line. No 
problem. After rebooting, I was able to successfully mount my linux 
drive thusly:

     mount -t ext2fs /dev/ad0s1 /linux

I transferred some files and was very happy.

Now here's the frustrating bit. Time has passed and the machine has been 
shut down and rebooted a few times. After that initial success, I have 
never been able to mount that !$!@#$ drive again. I invariably get a

     Operation not permitted

error. What gives? How can I retrieve my former happiness?
--Damon