Shut Down Problem

My Shut Down procedure is as follows:

1) Quit all apps

2) Select "Shut Down" from the Apple menu and click "Shut Down".

Recently however on clicking "Shut Down", the menu at the top of the screen disappears and the computer freezes up forcing a manual shut down using the power button.

On starting the computer and logging in I receive a message:

"You shutdown your computer because of a problem. If you want to open the applications that were open when you shut down, click open. ..."

It seems to be a finder problem as if I force the finder to relaunch before shutting down the issue does not occur.

Solutions please?