I had a strange issue with these that I've never encountered before. I installed them either the day or the day after they were posted here and everything was fine. It was on a 5770 Win 7 64. Clean install, safe boot, driver sweeper, the works. Worked fine since then, through multiple reboots, game play sessions, etc. But then this afternoon I went to turn on the computer and I noticed right away that Windows was in a lower resolution. I check device manager and sure enough the Windows VGA driver was listed.
I had a heck of a time getting the video card to install another driver. I did the whole clean install thing again a couple of times and each time the CCC install software zipped right through the process much faster than normal and wouldn't ask for a restart afterwards like it usually does.
After about six or seven clean driver install attempts I finally got it to properly install the 12.7 betas and now everything seems fine again.
I have no idea what caused this issue for me but I'll sit on the 12.7's for a while now since they seem to be working fine. I wish I knew what happened though, it was like the software refused to acknowledge that I had an AMD/ATI card physically installed. I"ve installed hundreds of drivers in my life and this was a first for me.
But, it's all good now so just reporting what happened to me.