I can no longer move my viewport using the mouse. The arrow keys work, but I would rather use the mouse. Any suggestions as to why this is?

Are you running the game in windowed mode? If so, you'll have to use far sides of your screen, not the game window. If not, a restart of game usually fixes any kind of weird mouse behavior.

A restart works, but after a few time playing it the problem returns.

Have you tried setting your Mouse Scrolling Speed?
Also, some Video Options might fix the thing.

yes, I've tried resetting the mouse scrolling speed. it doesn't seem to work. I have no tried anything in the video options, though.

same thing going on with my game...was a solution ever put forth on this?
Kind of makes navigation difficult.

JS

make sure that you don't center the nameless one (C shortkey)