This morning when I started IDEA, no files were reopened from the previous day's session and the directory that was open (expanded) in the Project window showed "loading..." (in grey). All other directories can be opened (and closed, repeatedly) without problem. There is no CPU usage. I've quit and restarted several times. I've resynchronized the project several times. I've closed and reopened the project. All to no avail. The rest of the UI seems responsive and all the other UI state (besides open files sometimes) is remembered from one session to the next.
I can use "File -> Open File..." to open files ... sometimes. When I open files this way the structure view is always displayed and properly populated but the file contents itself sometimes does and sometimes does not appear in the editing area.
This is happening with Selena 7255 under JDK 1.5.0_12 and 1.6.0_02. Switching to 7269 is the same. (Furthermore 7269 requires JDK 1.6 and the slow scrolling but persists under both builds, so that's not an option for real work. Furthermore, 7269 has exhibited other more severe and less repeatable symptoms.)
Lastly, over the many times I've now shut down, reconfigured (changing build and / or JDK) and restarted, I've seen other non-reproducible problems, mostly of the form of non-actions (other hangs, failure to open files, etc.). Because I cannot repeat them, I cannot accurately describe them.
The only thing that's 100% reproducible is the "loading ..." hang on that one source directory.
I'm at my wits end. I can scarcely work with IDEA at all like this.
(And if anyone is going to suggest I file a bug report, then you're going to have to tell me how to categorize and characterize it, 'cause I have no idea what's up with this.)