Subject Issues migrating from FB 1.5 to 2.5

I have an app that's been working fine for years on an XP box with FB 1.5. I upgraded to a newer box with Win 7 and installed FB 2.5. The app works great for about 95% but I get the following error under certain conditions:

Application Error

General SQL Error

Column XXX.YYY cannot be repeated in INSERT statement.

At line 6 column 78

Is this due to a change in the way strings or INSERTs are handled ? Are there any solutions (I do not have access to the application source).

Thanks in advance for any advice.