2003 Oldsmobile Silhouette Front axles keep breaking

I've replaced both half-shafts in the front several times over the past 2 years. My problem began when, in December 2012, I replaced the engine mounts, and both half-shafts at the same time. No I'm replacing the shafts about every 4 to 5 months. I've replaced tie rod ends, both hub assemblies, engine mounts, and have no clue what the problem is. I've been told that the engine could be "crooked" or out of align, and that could be causing the outer joint on the half-shafts to fall apart. Thanks for the help.