Here is the main problem:
http://news.softpedia.com/news/NVIDI...e-215493.shtml
It is a serious issue for a new OS on the market. But that's the inevitable result of the hustler's business manner in the industry. Besides being a writer, I have been an IT consultant for the last 20 years. My personal golden rule is: Never buy or upgrade an OS (no mater for Mac or PC) after the release. Wait at least 6 months before doing so. Otherwise prepare for frustrations.
And here is some solution to the problem:
http://support.apple.com/kb/HT4764
Good luck guys