Is there a Data Dictionary in Flash Fla's

I have been getting sporadic errors after deleting a symbol then recreating the symbol and making a past used instance name.
Sure my current workaround is to use changing the name by adding an extra letter. Eg if instance GreenHill of symbol GreenHill, causes a compiler error
I now use instance GreenHillB of symbol GreenHill.
//
To check that this is a real issue and not me having left some instance lying around, I have deleted all my symbols in (a backup version) then created one with a new symbol GreenHill and Instance GreenHill, and the problem persists.
//
So my guess is a data dictionary or PCHs of some form are to blame.
//
So is there anyway to flush the system of these things?