If you install the lastest version of Gaim but it doesn’t show its window, and you also installed Cygwin. Please check if there is c:\cygwin\bin in your environment variable PATH. If it does, delete it and your Gaim may run fine.
Kirin downloads Gaim 1.5.0 and also installed Cygwin. After installation, Kirin launch Gaim but nothing happened. Kirin check Task Manager and sure that Gaim was running.
There are some discussions in bug-list of Gaim, and someone suggested that.