QUOTE (Pessimist Prime @ Jul 28 2007, 04:43 PM)

The ice was melting on Megatron, enabling him to come online and wreak some havoc. The ice itself didn't physically restrain him anyway; it was the extreme temperature.
Actually the ice did physically restrain him.
Here's why it would work too...
1.) They sprayed Bumblebee with a freeze liquid and as we clearly saw, he was fully functional and fighting back with every last bit of energy he had. It did, however, slow him down some. (So the extreme temperature didn't imprison his body, they didn't do it to Megatron, either.)
2.) As previously mentioned, they were able to have deep space travel, and it didn't freeze them. (Again, extreme temperatures didn't do it.)
3.) Megatron was not only frozen by the temperatures, but since these Autobots and Decepticons have openings all over their bodies (Megatron for sure, look at the animation model) the temperatures could get inside their bodies (which would slow them) but not entirely freeze them. No...it was the arctic water spilling inside of Megatron's compartments and servos and whatnot, and then freezing solid, locking him up from the inside out. Then you add on the extreme cold...and yes, the ice would indeed physically restrain him. And it did, since his original discovery in 1895, and when he crash landed over one thousand years ago. They moved him in the 1930's and he was frozen solid (and kept that way for the duration of the trip) because if one piece of ice came loose, he'd have reactivated and ripped their asses to shreds.
Also, take a look at the Voyager Megatron figure. Plastic ice is implemented in key spots on the body to convey that it was physically a part of him.