I have had ETO 1.4 running just fine, but every time I have tried to update to 1.5, I keep getting this error message- UnitData Model "h75a3" already used! And it won't start. I have not added anything to ETO, have not deleted the H75, so not sure what's going on. With every installation of the next version of ETO, I have run the program to delete obsolete aircraft, and the BDP zapper. Would like to know what is causing this error and how to fix it, hate to reinstall, but not sure how to get around this stupid error message I keep getting. Beginning to think it best to stop at 1.4,lol