I've installed the sim to my USB stick.
What I'm saying is that he may have copied the incorrect files while sending them to you. It sounds like his files are stored in VirtualStore. This would happen if his pccsdb files are in a protected location (such as Program Files). If this is the case, I think the following is happening:
1. He opens the .pccsdb in PCCS. Since PCCS is not run as admin, it creates a "virtual copy" in his VirtualStore directory. The effect of this is when he tries to open the .pccsdb from PCCS, it loads the virtual copy but in all other cases it loads the original, locked copy in the Program Files directory.
2. He emails you the copy from the Program Files directory. Since the modified DB is the virtual copy and he is not selecting the .pccsdb from PCCS, instead the brand new clean copy has been emailed.
3. You receive the clean copy without files.
In the case where he is renaming Clean.pccsdb and opening it up through PCCS, this time (1) above happens again, except that it happens to the renamed copy.
If this is indeed the case, all he needs to do is send you the virtual copy from the VirtualStore directory, the location of which has been published before in this thread (may even be in the opening post).