"Dope" demo bugs (DOSBox-X's fault)

BUG: Noticeable pause of music at points where VGA BIOS is called to set video mode during demo

BUG: You can only run the demo once. Additional attempts log "illegal instruction" messages and
     crash back to the DOS prompt. You must close and reopen DOSBox-X to run the demo again.

 - I know for a fact that is not a feature of the demo. Having run it on real hardware, I know
   the demo can be run again after the first time (though it is not reliable at reinitializing
   the GUS to a known state).

 - The debug messages from DOSBox-X are:

Warning: Illegal read from b66b1da, CS:IP 8: b66700a
DYNX86:Can't run code in this page!
Warning: Illegal read from b66b1da, CS:IP 8: b66700a
Warning: Illegal read from b66b1db, CS:IP 8: b66700a
141992554: CPU:CPU:66:GRP5:Illegal call  7
Warning: Illegal read from b66b1da, CS:IP 8: b66700a
Warning: Illegal read from b66b1da, CS:IP 8: b66700a
Warning: Illegal read from b66b1db, CS:IP 8: b66700a