After a couple of days away from building my route I decided to add a little more today whilst away from work for the day. Bad news is I now can't get Rail Works to launch, I get the following error:

I have tried verifying the game files, de-fragged the game files and even re-installed to a fresh install, still get the same. Can anyone think what the issue is please?
The error seems to be the GameManager.dll
Thanks in Advance
Paul