We started experiencing the following error on our PC laptops running XPress Pro 5.7.2 when trying to open one project on our Unity:

Assertion failed: charCnt

File: \coresw\core\filesys\AWinFileSystemObject.c, Line 253

The project opens fine on every other system. These are the only two PCs on ethernet (opens fine on Macs on ethernet and PCs & Macs on fibre) and they both have the same error. Opening other projects on our Unity is fine from both machines. I don't know what could have changed in the project between when they worked and when they didn't.

I've deleted user settings for the laptops on the Unity, trashed local settings and databases, and actually just reinstalled XPress Pro on one of the laptops. The issue persists. Any and all thoughts are greatly appreciated.

My first thought is eliminating the project all together. 

What happens if you create a new project and just drag the important bins (from the problematic project) into the new one?  Any problems opening that one?

The problem actually resides in the project settings for those specific Avid stations--basically, there's a folder inside each project for every project opened off the unity that relates to every bay that opens said project.  So if your laptops are called "LapAvid01" (or whatever), then the project should contain a folder called "LapAvid01" inside it (assuming it's been opened from the unity).  There's project settings inside that folder.  I would guess that those project settings are causing a problem for whatever reason.  Trashing those folders (after making sure noone has hidden bins inside them) may just fix your problem.  But the uuber fix is to create a new project and drag the bins into it. 

If that doesn't solve your problem, then there's a problem with a bin/media.

Hope that gets you rolling

~Hammer