Saving Error. What can i do?

[CalypsoArt]

I get this error when I save my model. How can I find and remove the problem entity?

Results of Validity Check.
*** Problems were found that could not be fixed! ***

The entity at address b4a75800 has an invalid id (0) destroyed (0)

[CalypsoArt]

Getting these errors on every model.
Here is the latest.

Results of Validity Check.
*** Problems were found that could not be fixed! ***

The entity at address 6d3dfca0 has an invalid id (0) destroyed (0)

[citygrand]

How about copiyng objects to new file and trying to save them?

[delgash]

Copying the project into a new one help a lot, thanks.