iTunes 9.0.2 hangs on launch on Mac OS X 10.6.2

iTunes 9.0.2 hangs on launch on Mac OS X 10.6.2

My iTunes 9.0.2 hangs on launch in OS X 10.6.2. This doesn't happen all the time, only if I've been running for a while. Then it will recur until I restart. Similarly Safari 4.0.4 will hang in the flash player plugin when about to play a video. If I restart both these problems go away until later.