how frequent is it flashing? may be finder in a relaunch loop. can you open things in your dock and use them?
Was your entire menu bar flashing, or was it only either the left or right hand side?
Sorry for the delay in responding but I've been away and off-line for three days.
The entire menu bar was flashing and it was fairly rapid....sort of like an "Eat at Joe's" neon sign. During the period it was flashing nothing worked. It hasn't happened since I made the iSync Preferences change, and everything has been working normally.
ryck