Like many, I have frequent CDTs when colonizing planets. If the devs need another SmartException report on that, just let me know, for now I'm assuming that they've received numerous reports of this.
Second, the game hangs a lot on my machine. It seems to be related to autosaves, as it happens more frequently when the autosave is set to 1 compared to 24 (on a side note, unchecking the autosave box does not turn off autosaves). Basically, the dialog box with the GNN robot pops up with no text in the window, and it just sits there, with no UI element active. I've let it run for a minute or two without any response or activity before invoking the task manager and killing it. This is on an AMD64 3400+, 1.5G RAM, WinXP SP2, GeForce 6800GT video card, and a half-full 30GB IDE HD. Hmmm... forgot to check the debug log to see if anything turns up there.
Lastly, not a game-breaking bug, but more a UI quirk (I know, UI is Beta 2, but this might be an engine bug), if you drop too few people, 500K for example. on a new planet, you wind up with an invisible planet. Even zooming in all the way, you don't have a planet graphic or an owner icon. I suspect this isn't an engine issue, since it seems to have no problems presenting a sensor drone however small.
EDIT: O.K.. really three issues, but I wasn't sure if the last one counted.