Review the advice given here:
In particular, there is a diagnostic script that can be run (with root privileges)
Often the first time you run this script, it will note there is an update available, and ask if you wish to update. Select YES. If you are running this in a terminal/konsole with root permissions, the script will update. Then run the script a second time. When it is complete, it will pass you a URL. Take a look at the contents of the URL, as it passes to you useful information. Also keep a record of the URL provided by the script as it can come in useful for passing to others who are trying to assist you (on one of the forums, or on an IRC channel). Then go to the next step of this guide.
Others may be able to assist further, once you have posted the URL to the generated output.