Yep, tried releasing ip's , and then rebooting. On reboot, no ip allocated.
I checked the var/log messages file, nothing in there to tell me there is an error.
I have reported this to the bugs department, and they have confirmed, it is a bug and they are going to lok into it, as they have also got the error on their pc's.
I will hold on for a few more days to see if it gets fixed, otherwise, I will go back to v5.0.
Scott