[Dx4win] "Cannot focus a disabled or invisible window"

[Radivoj Kar, F6GNZ]

Hi,
On mt Win7/32bit laptop I had several times following error:
After stopping radio and switching it off, clicked Exit to close DX4WIN. But instead of exiting, only the log window closed, all others remained. Clicking on Fil-Exit or ant other command on DX4WIN command line, results in Error message: "An exception occured. Cannot focus a disabled or invisible window"...All other windows remain active, even the cluster continue working and I can send commands and receive messages, but the main command line is like dead!!! Task manager shows program as running, and says it is waiting a command from me. Have to close it by "force", HI!
Any reason for thios???
73, Radi F6GNZ