My App was working fine in Windows Server 2008 and 2012. Few days back, I had to format server due to some technical problem and reinstalled Windows Server 2012. After this,above said error appears once in a while in a day and I have to ask my users to either use another executable with diff. name or ask them to leave that particular instance of Exe.When none of the users use that particular instance,it is then available for reuse. What might be reason for this as before installation, my EXE was working perfectly fine even in Windows 2012.