I tried that in Monkey 1 and it actually worked but... I could only do two things (as in use mouse button twice to make an action) and then it stops working.
I have this EXACT same problem on my CDTV. It's the official Monkey Island game (no pirate copy or anything) booted from an attached floppy drive. I have even gone as far as disassembling the game during run time by freezing it with an Action Replay cartridge on my A500 (where the game did not have any problems, btw). It seems to be programmed in a system friendly manner, doing Intuition calls etc.
But alas, I have never been able to pin point where it went wrong and more or less lost interest and now I don't really have the time anymore. A shame really, because I'd love to burn this game on a CD-R and play it on my CDTV.
Have you tried removing your HDD and/or accelerator card to see if that solves the problem. It worked fine on my A500.
Here's some of it on my blog:
http://www.easygalaxy.net/cfamiga/2009/01/captains-log-star-date-2009011-1.htmlhttp://www.easygalaxy.net/cfamiga/2009/01/captains-log-star-date-2009011-2.htmlhttp://www.easygalaxy.net/cfamiga/2009/01/captains-log-star-date-2009012.htmlWish I had the time to dig my teeth into this again.. If anyone manages to find an explanation for why this is not working it would solve a long standing mystery for me.