Found an online reference that suggests that the 8000000B is a Line F emulation error that is when you try to execute an FPU command without one being present, or a problem with 68040/060 library. I seem to remember that either the 8000000B or ....3 were pretty common Gurus.
They also give a great suggestion that has worked for me many times. Edit your s-s to run SnoopDOS, which will open and show which programs / fonts / functions etc. are being called. This may help you pin down where the error is occurring. You didn't say where the error is popping up. Though the fact that two different disks cause it does somewhat point to hardware outside of the disks; it's unlikely that a virus or bit error would cause the same Guru in both HD's. So doing the "push the chips down into their sockets" where applicable, as well as reseating the accelerator carefully, those are both useful things to try.
Finally, it's a lot of trouble, edit the s-s to periodically tell you how far along it has gotten by printing messages. It has been SO long since I did this that I can't remember the syntax and don't have the Amiga handy that I did it to. Just insert lines, have it ECHO to the screen something like "Made it past the user-startup", etc. If you can Ctrl-D out of the Startup-sequence or boot from a floppy to make these changes with a text editor, it will help narrow down where the error is coming from.
Do the chip and board re-seating first and then try the software solutions is my recommendation. Best of luck. :-)
