Problems with Thunderbolt Port and HDMI

I have a late 2011 13" MBP a few weeks ago and have this Thunderbolt to HMDI adapter. For almost one year the cable and the port worked fine. Since I updated my MBP (don't know exactly when or which of the thousand updates you receive each month) the port and cable stopped working. When I plug it into my Macbook, the laptop's screen turns blue for a few seconds, but the TV continues to say no signal. I need to press the ON button for several seconds to reset it because the laptop completly freezes. I know that the cord isn't busted, because I tried it on another Macbook and it worked within seconds. For sure I have the latest Thunderbolt update (1.4 I think). Please help! Because I'm regreating I bought a Mac on the first place, I never had an issue before...