Every message regardless of account gives error

I have WLM version 12.0.1606.

I have it checking multiple iMap, Pop and two hotmail accounts. I have
always had a problem since I started using it marking mail as Junk and
getting an error message:

The selected message could not be moved. There was an error.

Now today (out of blue) I cannot reply or forward any email regardless of
the account it was downloaded from. Every message gives the following error:

There was an error opening this message. An error has occurred.

Unfortunately that is the extent of the message so doesn't give much help or
clue. I have searched forums and google without much luck.

Thanks.