I just noticed this one. I went in to add a new column, after doing so and selecting "OK" to apply the changes, the scroll bar on the bottom (indicating the ability to scroll left and right) disappears. Even on a small amount of files where you would normally be able to highlight a track and then use the scroll wheel on your mouse to move left and right is a bust after editing the columns.
You don't even have to add a column for this problem to present itself. You can remove a column, hide a column, un-hide a column... even simply enter the settings window and select "OK" without making a single change, all will trigger the lose of scroll ability.
Only way I've found to get the functionality back is to Refresh (F5), Change/Add a Directory or restart the program. It's annoying, though manageable when messing with a small amount of files, though if you're working on a large directory and trigger this, it can be a real pain.
Vista BTW, any other details needed, lemme know.