My first guess would be that the culprit is the “virtually stuck key” syndrome.

Sometimes the computer misunderstands the connection to the computer keyboard, and wrongfully gets the idea that a key on the keyboard is constantly pressed down.

As a result metatools triggered by that particular key get activated.

The usual fix:

Log out, and log in again.

This happened to me too.  As it turned out, one of my keyboard keys actually was registering as "down" due to some crud that had gotten wedged under the key.  Resulting in the metatool being triggered for that key.  

Hey there. Thanks for the replies. The problem is, it's a brand-new computer and I'm not using the keyboard, it's the mouse. This happened when I first got finale 2014 as well. At this point I get some work done, then the problem happens so I log out and log back in again.

I have the same problem. I have the latest version (25.5.0.290) When I click with the mouse, Finale instantly enters an 'mp' (the previous time it happened (last month?) it was 'mf', I think. The metatools work but I want to choose an expression not assigned to a metatool, so I'm shafted. wotsupwivit??? I tried re-starting Finale but get same problem. I've used Finale since v.2 way back in the days of Windows 3.1, so I know what I'm doing. This latest version (together with Windows 10) seems vey buggy... :-(

As Peter said, the most likely culprit is a (virtually) stuck key, which would not be Finale's doing but the computer keyboard or OS.

Adrian,

How, then, do you explain that the VSK only shows up in Finale? Something in the software is triggering it, even though nobody can figure out, what.

Hi David,

You don't happen to have anti-virus software like Webroot installed do you? I have seen, from time to time, where Webroot will actually cause metatools to act like there is a virtually stuck key (as mentioned above). Please check out this knowledge base article for more details.