About 10 minutes into the dive, my computer started beeping at me. I looked to try to figure out what was going on and realized that the computer had reverted back to Air mode and that it already had me going into deco. I was only about 1/8th of the way into my tank and certainly didn't want to force my 2 other buddies to cut their dive short. So decided to keep diving and would basically go by one of my buddies computers since it was correctly set for Nitrox 30%. We went ahead and had a pretty nice dive. After going through a bit over half our tanks, we decided to head back up and do out deco stops. My buddy had about 8 minutes of required deco according to his computer, and I had 28. What a pain. I did not want to violate my computer, so decided that I'd wait it out. So I hung and hung and watched practically all of the divers still down come around me on the line. Most had already boarded the boat by this point. There were still 2 straglers who happened to also be the first ones in the water. They were actually diving with rebreathers. Once they boarded the boat, I knew that I was the last one still in the water, and my computer still wanted me to hang for 10 more minutes (though my buddy had been finished with his deco for about 10 minutes). Although I still had about 750 pounds left, I decided to not make the whole boat wait on me, just to keep the computer happy. So I came on up and it beeped and beeped at me; then went to "Err" message, and I was locked out so to speak for 24 hours. I went ahead and made my next dive using my buddies spare computer (that he had taken on the previous dive as well) and used it for my second dive