Hmm, I only encountered that bug once and don't know if I can ever reproduce it, but as far as I remember I proceeded as follows:
Round1:
I started the game (downloaded here) in dosbox and played a new game (cheats disabled), saving at every possible save-position to be able to reload in case of unexpected disaster. I reunited with my shadow and crossed the invisible tiles. At the next screen with those falling tiles I saved the game and went to lunch, but obviously forgot to pause it.
When I came back after about 30 mins the intro/demo mode had been playing for quite some time. Thus I reloaded the game, finished it and then started all over.
Round2:
After finishing level1 (I think I had not taken the sword but outmaneuvered the guard) I was right back where I last saved the game and just had to run past that falling tiles, climb up to Jaffar and beat him. The hall of fame entry shows 56:22 remaining for this round...
I'm not sure about this, but I think I also had some problems with the copy-protection showing up despite of the crack during round1. This happens to me every now and then, I don't know what exactly triggers that. Maybe this hasn't even to do with the bug, maybe it was the lunch...
Anyway, I'd say that from a dramaturgical point of view one should delay Jaffars defeat to the last possible moment. For instance, the end of 'Goldfinger' would be much less funny if James Bond managed to turn off the nuclear device with 30 minutes remaining 'til total destruction instead of 7 seconds
