Characters change to asterisks

[thomasv]

Every once in a while all the characters in my document change to asterisks (it happened in two different documents, both created on my own laptop). There was no immediate cause (I didn't press any button). When the characters have changed, there seems to be no way to undo. I have already reinstalled MS Works for Mac and updated the software. Can anybody help? Is this a known problem?
Thomas

 

[chscag]

Moved to correct forum. Please read forum descriptions before posting. Thanks.

 

[toMACsh]

I have already reinstalled MS Works for Mac and updated the software.

Do you mean MS Office for Mac? And, which application from that suite is being affected?