I recently upgraded my OS to Leopard and found BC2 acting a little weird, so I upgraded Crossover to Games 7.1.1 and downloaded Beyond Compare 3. Some of the initial weirdness has gone away, most likely from Crossover. But I did immediately run into a problem when I double-clicked on a pair of files to compare, and instead of opening up a new tab, BC3 just quit altogether. I changed my preferences to open comparisons into new windows instead of tabs and it seems to be working fine so far.