I'm on the second "level" where Manny's running a casino etc. and all of a sudden, he starts walking really weird. His legs aren't moving and he's like floating around and it's really hard to control him. This must be a bug, but how do I fix it? Any information is appreciated!

A few questions:
Do you have the patch... that may help but not for sure
Also some video cards like my old one acts up like that in the game (Voodoo 3000) you can generaly just keep playing 'till you get to the next year or area and it will be cleared up or you can start from your last saved game. Generaly the problem does not occure twice in a row.

Hmmm. If it is a card-related problem, turning off hardware-acceleration could fix it (and make the graphics look crappy).