Re: Disappearing photoshop!
I read an article on Adobe's tech support sub-forum recently where menu bars disappearing and a very slow redraw rate was caused by a damaged font in the fonts folder. The solution was to create a new folder on the desktop, move all the fonts there, close Photoshop, put the fonts back into the Photoshop fonts folder and relaunch. As Photoshop reloads the fonts, it will tell you which font (if any) are damaged. That single font can then be deleted and redownloaded if necessary.
This may or may not be the cause of your problems, but might be worth a try.
Edit: Try disabling the font preview first. That alone may solve the problem, and point to wether or not this is your culprit.
-Joe U.