You bet man. See, the problem is, the files may LOOK identical without de-compiling them adn looking at each line of code line by line comparing it to a known-good copy. You've got to remember, ANY change in so much as ONE CHARACTOR will cause problems! I honestly think that, even if you're using an earlier version, a version later should still open your data files. Companies don't generaly make changes that eliminate the modules needed to open data files savedd by earlier versions. They would certainly loose ALOT of customers were they to do somethign like that. I strongly doubt that the problem is a copy guard so much as it is, you cannot retreive something that no longer exists. Given that that CD is cracked, there are probably SEVERAL bits of data that are simply not there any longer though the drives error correction THINKS it's done an adiquite job parsing what's missing.
Given how cheap versions like 4.0 can be had, I HONESTLY feel your BEST bet is to set the cracked CD aside for now, and try a new copy. This copy:
... is $14 shipped to your door and ends in about 9 hours from now. I strongly doubt it's going to go much higher than the opening bid. ASk yourself, how much time have you spent trying to copy your older version, let alone media you've burned, adn how much is each hour of that time worth? Wouldn't you rather be doing something else?