From time to time I'll be working on a drawing for awhile, when I'll go up to the menu and find that ALL the menu items in all the menus are greyed-out and unselectable. The only way to bring them back is to save (using command-s) and quit (using command-q), then reopen the file.
Any thoughts on what could be causing this, or anyone else seen it? Unfortunately it's not exactly reproducible at will and I haven't yet noticed any particular pattern of what causes it, other than that it usually happens after I've been working for a while.
Running Mac OS X 10.4.6 on a dual-G4 with 2GB of RAM, by the way.