Wrong major or minor number

I have been playing with the LVM stuff for a few days now. I created everything, got reiserfs
on my logical volume, everything worked OK until today. I don't think I changed anything, but I can't mount it, I get the error:

/dev/volgrp1/software has wrong major or minor number

Reiserfs has a FAQ on this, and it states that the reiserfs code is not available to the kernel or it isn't a module that is available. But...I have another partition, on another disk, that isn't in the LV, and it is reiserfs, it works fine.

Any help?