I agree that you need to get someone from the IRS who can explain the "error" (which, if it is exactly as you stated, NOT an error. My kids had summer jobs when they were in high school and college. They always filed a return and did NOT claim themselves (checked "someone else can claim me on a return") and we never had a problem. I filed my regular return and claimed them as dependents. As Critter stated above, there might be some ID fraud. (We also went through that ordeal). Call them next week and good luck.
