Where is the mutex of BoS?

[cro888888]

I have a setup which puts entire IL2BoS into an external disk using Steam. One day I accidentally unplugged it and found it always says another instance of IL2 BoS Editor or IL2 BoS is running. I have tried reinstalling on both C : and D :, executing with disk plugged and unplugged, not working yet. If it's a mutex issue where is the mutex? If not what would it might be? Thanks for the help. P.S. I deleted all files left there during reinstallation so no logs