microsoft word/email message/title bar is flashing and locked up

[Flashing Title Bar]

I'm trying to write an email message in Microsoft word - then for no reason
the title bar starts flashing and the word document bar at the bottom of the
screen flashes orange too and my document is locked up - why?????

How do I unlock my document?

 

[Suzanne S. Barnhill]

See “The Word title bar flashes or the Word program becomes unresponsive
when Word is runningâ€
http://support.microsoft.com/?kbid=812075