Error synchronizing Project Server and Active Directory resources

I have find some resources which cannot be sync with Active Directory and makes that Published database gets in an inconsistent state. For these resources you will get an "Unknown Error" when you try to modify them and if you try to remove them you will find that resources are cheked-out. As you can see in "force check-in enterprise objects" these resources are not listened as cheked-out.
Another sympthom of this is that users which are in an inconsistent state have it's status as innactive, so they can't get in Project Web Access.
How to monitor the error?
If you take a look to the Published database you will find in the MSP_RESOURCES table that users which are in an inconsistent state have his RES_CHEKEDUOT_BY filed to a empty GUID.
Of course it is not correct that value since this is what is causing the error.
How do we solve it?
1. Open an issue with Microsoft or install its hotfixes.
2. Run a sql squery wich will get the user in a consistent state:
update MSP_RESOURCES
set RES_CHECKOUTBY=Null
Where RES_NAME='Name_Of_The_User'
Of course the second option is not supported by Microsoft so you will loose Microsoft's support if you modify the databases and you don't reurn them to its original state.
After doing that you will be able to modify user's state from the Project Web Access site.