This is a bug still in the beta from the original release regarding the way in which MA counts turns in replays. This also effects the automatic replay naming:
http://massiveassault.com/forum/viewtopic.php?t=829
To follow-up this bug, let me say that the problem only occurs when the person who's replay it is played as the FNU. It happens regardless of map, only side has any effect.
Also, replay naming in single-player fails to insert the players name in the replay name, only that of the AI. However, the name appears correctly during playback.
I still would like to see a bigger replay window, either through scaling with the resolution, or the ability to resize it. Replay names never fit in the window.
I still experience the laggy graphics effect (on load, everything lags until I go into Graphics Options and click Apply, then it's fine. I have a Radeon 9800 Pro and have had this problem under the 4.1, 4.2 and 4.3 Catalyst drivers). I'm also sure you're away the problems under Hardware sound when using an Audigy/Audigy2 continue.
Irritatingly, replays are still listed by date of file modification, with no way of reordering them.
For some reason, whenever I load MA, and this pre-dates the beta patch, I have to click a menu option twice for it to work. Once I've done this once after loading the game, all buttons respond to a single-click.