I think that this is a problem in the ClearCase plugin (2.0). Not positive, though. When I try to open a new project - whether by reopen in new frame, reopen in this frame, or close project followed by reopen - IDEA usually freezes up a bit afterward, often when doing a ClearCase operation, or when doing File>Synchronize. In the case where I reopen in a new frame, I can occasionally able to get by until I try to close one of the frames, at which point IDEA freezes. By "freezes" I mean apparently quits processing the event queue (Windows XP SP2). The application frame is redrawn, but that's all. No obvious CPU, disk, or network activity. Attempting to close IDEA using the Windows Task Manager gives the expected "application is not responding". Other applications proceed normally. Killing IDEA with Task Manager and restarting it gets it back under control. I am able to close one project in IDEA, close IDEA, restart IDEA, and reopen the new project. This is, of course, a fairly slow workaround with large projects. The two IDEA projects are both ClearCase UCM, but are in different UCM projects and in fact are in different ClearCase VOBs.