Bitoy will be able to help you better but just a few pages back I had issues and found..
-Make sure you have none of you're files in your MyMastercoins folder set to read only! (You can do this by Right Click: Properties and make sure the box is un-checked) (Additionally make sure you have Full Control as an Administrator, you can do this as well by Right Click: Properties: Security make sure you have "Full Control")
Though that shouldn't have anything to do with Exception thrown: File not found.
I had a issue with the main setup.exe so I actually go into the MyMastercoinsTCW_1_0_0_1 folder and run MyMastercoinsTCW (Application).
None of the files are read-only.
How did you run MyMastercoinsTCW (Application) from the MyMastercoinsTCW_1_0_0_1 folder? If I try that, I get: ' You cannot start application MyMastercoinsTCW from this location because it is already installed from a different location'.
I have MyMastercoinsTCW (Application) twice, once in the mymastercoinsTCW folder and the other in MyMastercoinsTCW_1_0_0_1. If I run the one from mymastercoinsTCW I get the file not found stuff again. Is having MyMastercoinsTCW (Application) twice the problem?