The problem is (most likely) in one of three areas:
1. the software
2. the preferences
3. the data file

At this point we can rule out #1 since you have switched accounts and the software launches fine.
Also, if you've deleted the preferences and the problem persists then it likely isn't #2 (assuming you got all of the preferences)

The next step is to take your data file into another account and see if it opens up. That way you can see if it is the data file.
_________________________
John Wallace
Now X Tech Lead
President, Now Software, Inc.