Hi, i started having this problem when i run the -server option too.  It happens when the computers are turned off unexpectedly.  I have four mining servers and at first just one was affected, so I just pointed cgminer at the other server which was working, but now all of them are affected so I am forced to find out whats causing the problem.  Once I figure it out I will post it here.

This is what i have tried so far with no success:
Delete all files from the bitbar folder in the appdata directory (make sure you make a backup copy of wallet.dat before doing this)
Delete the bitbar-qt.exe folder with all files.

This did not fix the problem.  Will keep you posted with my progress.