I've had Photoshop get stuck in a modal dialog box several times. Hitting OK or Cancel doesn't close the box. I can select some Photoshop tools I can't normally select when in a modal dialog. I have to force quit Photoshop CS5 and lose my work.
I just noticed the last couple of times this has happened that ESTK CS5 had crashed in the background, even though I wasn't doing anything with it.
I am the only one at my workplace that uses ESTK and many users on otherwise identical machines have not had the modal dialog issue.