I have the latest installation through Galaxy, and when I launch the game I get an item on the taskbar and lose mouse input to about 80% of my screen; I can use about 20% on the far left side. I've let it hang there for about 20min and nothing happens - I need to open the task manager and navigate it using the section of screen I can actually use and close the program.

I've played it on this computer before without issue, and tried verifying, then uninstalling (including all savegames) and reinstalling but am still getting the same hangup. Anyone come across a similar situation before and remember how you solved it?

Usually I would suggest you to try using a compatibility mode, but this can't explain why you were able to play the game on the same machine in the past.

I don't use Galaxy, so can't advise through experience, but have you tried disabling the overlay?

Success! For anyone else running into this issue, open the Config and switch to 1024x768 resolution under the graphics tab :)