Another datapoint. I'm 99% certain that the crashing only occurs when using the keyboard to deal with the "save as" dialogue rather than the mouse.
I can pretty reliable crash by clicking "save as" then typing in the name of a directory I want to change to (or a filename I want to save as) and hitting enter. If instead I click the directory, filename, or "save" button with the mouse, it either never crashes or is much less likely to crash. I continue to lose a lot of data because of this bug, however.
