Ok, I just learned about another little bug that people who use multiple screens should know about.  If you have two (or more) active monitors, it is possible to loose ACL completely from your monitor or to have it freeze up on you completely. 

I don't know the technical details, but it basically boils down to the fact that ACL wasn't written with multiple screens in mind and sometimes misplaces the project or screens. 

If you ever loose ACL or can't get it to respond, and you use more than 1 monitor, try the following:

Alt > Space > M

Then hit the arrow buttons a few times.

Then move the mouse. 

If the problem stemmed from the multiple screens, the missing screen should appear on the project.  (Oh you have to have ACL as the activeproject in the view.  If you are working on Excel, it won't work.)