If I click cancel, try again, or continue the message will reappear every time. The only way to get rid of the message is through task manager by force removal. However, if I then try to reopen WinSCP again I get the same error message. The only way I found to fix this and get WinSCP to work again is to restart the computer or to insert the disc back. This bug needs to be fixed as soon as possible as people that are all the time using CD's/DVD's in the computer have to restart every time or insert a disk. This error can be reproduced on 5.1, 5.1.4 and 5.2 beta and probably more.