Jeff,
First, the bug report will go directly to support, so they will have information we don't have. As Adam said, can you reproduce it. What version are you running? What were you doing just before?
I have used AC in every version since its inception and that has never happened. And, Jon, will tell you as my programmer, Ed, will tell you; if you can't reproduce it (meaning they), then yoou can't fix it.
If it happens again, I would first, run the AC Utilities and fix the database, and two, re-install. So, in order:
Utilities
Reboot (fixed over 50% of all Windows errors)
Reinstall