Legolas8181 :
ab3x :
Because Black Flag is old now the version of PunkBuster won't be the same as to what it is now so it causes crashes and other problems, so yeah update PunkBuster and you should be good to go
Would that actually work? How do you know?
A few years back I used to play Call of Duty 4: Modern Warfare which ran on PunkBuster and after a while of inactivity I decided to play again, to then come to the conclusion that it would keep crashing and booting me back to the desktop everytime I connected to a game. Turns out all I had to do was update PunkBuster and there you have it, all working fine again, so I'm about 99.9% sure that this is your fix