I've had serious problems with Eclipse's autocomplete/intellisense prediction feature. It often begins listing identifiers and then just hangs indefinitely. I don't know if the fact I'm developing using the Windows build is significant - it is Java after all so it should be platform agnostic.

I seem to have bad luck with IDE's though. I develop using Visual Studio 2008 and that has some horrendous problems, though VS was never known for stability (six service packs for VS6, anyone?)