I smoothly downloaded, installed, and runned without ANY problems. I could use it 2 times. The next day i tried to install, and I needed to enter a serial while I had 28 more days. Its the same window when u start up AE cs3, and clicking on ''Continue Trial Version''. When i start up now, that windows pops up, and I only can enter my serial, and I cant choose the continue trial option. Wtf???
Check whether you ran any other Adobe as trials in the past or participate(d) on any of the public Betas. The licensing system is rather picky about such matters and may mistake an old activation/ timestamp file that you never removed for a full product that has not been serialized correctly. In either case, the only ones that can help you is phone support by providing you with a proper timestamped serial for the rest of your trial period. Just explain the situation and provide as much info as you can give.