What's the install date on those 12.3s? 12.2 will cause graphical artifacts in Skyrim with the in-game AA turned on, and they also (just to add to the headaches) incorrectly report as 12.3 in the CCC.
The "real" 12.3s came out on March 28th. If you have an install date on your drivers of anything prior to that, you actually have the 12.2s and either need to upgrade or roll back your drivers.
If you do have the "real" 12.3s...it's also been reported that just a straight upgrade won't fix this problem. You need to uninstall 12.2 completely and then upgrade to 12.3. Either way, your best solution here is to scrub your current drivers and install with the 12.3s. Or roll back to 12.1 if you prefer. Whatever driver set works best for you, go for it.