When I close FAF client, I cannot start FAF client without restarting my computer

See subject. I don't know what causes it. It's very annoying.

Did you kill it via TaskManager already? Cuz smts it keeps running in the background -> Kill it, then it should open again as intented
(And make sure your TaskManager shows the 'hidden'/background programs as well)

Just kill the task in the task manager. But yeah, this bug should get fixed. The FAF client is a mess, most of the time you close it, it stays open in the background and even increases cpu load.