Cannot find or open a required DBG file

I keep receiving annoying
"Cannot find or open a required DBG file"
which slow down dramatically the aplication launch and close.

Why is this?
How can I avoid it?

To things that could make this appear:
-I've deleted all the obj and bin folders as well as some .pdb files :rolleyes:
-I've mixed two types of languages in diferent projects: VB & C#

Thx!

I've solved it re-inserting the new code into a older version (backup) of the project that didn't had does errors. The code, not the projects.