I am hoping someone can help me, I have been trying to figure this out for a bit now. I started off with Lion DP2 on my Macbook (Late 2008) when it came out and upgraded to DP3 and DP4 once they were released. The only issue I have seemed to find is that sudden lack of a working Mini DisplayPort. I have tried my MDP to HDMI and MDP to VGA attachment with no success, but yet they still work on other Macs. In the system profile I see... Display Connector: Status: No Display Connected Thunderbolt: No hardware was found. I have tried to find an answer to no avail. I am hoping the wise users of this forum can help with this issue. I am wondering if there is a file I can rip off my SL disc to overwrite a possible corrupt file in Lion. (but I have no clue where to look for that) Any help would be appreciated.