OK...I found out what it was. Its the Phpbb software that has a session cache limiter and when a user hits the back button it sometimes skips and jumps past the previous page and the form page "Warning : page has expired" will pop up .
I figured it happend when I clicked on my desktop to search for an item to attach to a PM and then returned to finish message , clicked in the Message window to type , made a few successive typing errors and to correct them , I hit the "backspace" button ,possibly twice, and my cursor ,somehow, was not set in the Message window,so it skipped back and ..........bye bye message ! Something to that nature.
