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I get a start up screen but it suddenly goes to Black and stops. It doesn't even get restarted.
This problem is so annoying. When I had faced this problem I tried many suggestions to solve this problem but none of them became successful. I was because I had not any backup for restore. As a result I was forced to reinstall windows. But you are lucky if you have the back up. If you have then try to restore it and your problem will be solved. Otherwise you have to reinstall it and unfortunately you have to lose your important data. To protect your data I can suggest you to use Ubuntu from DVD without installing and move your important data.