I think it's fixed! I checked the Task Scheduler, like NetServOps said, and found one line item that was scheduled to run every 10 minutes. "Firefox Default Browser Agent A99BB431EF49E2C3". I disabled it, and have not had the flash of the cmd prompt since! Thank you so much.
Edit: I'm new to superuser. I'm not sure if I could have selected a comment in order to give the person who answered, credit.