1. Os and Ae version specs
2. show us the full Ae interface and try to show step by step - write your workflow and what is happening. right now we can't be sure what's going on besides a mask path near a colored rectangle.
If making sure that you are viewing the Active Camera or resetting the Magnification ratio to Fit doesn't fix the problem try rebooting. If that doesn't get it try deleting your preferences. You basically mash down on all the modifier keys on the right side of the program when you open AE or go to Preferences>General and locate the preferences file and delete it.
Thanks for all the advice! This morning I completely reloaded the software (as opposed to a straight upgrade) and it fixed the problem. It's really odd to me that an upgrade wouldn't fix it and a reload would.