I did a search through the forum, and didn't see this reported anywhere else, so I thought I'd mention it...
Basically, it seems that when running Sins on an x64 OS, there are problems with some key bindings. It's easy to see- just go into Options -> Key Bindings and you'll notice that many of the bindings flicker between their appropriate setting, and random junk. This also happens in-game when you hover your mouse over a button and the tooltip pops up to give more details.
I was previously running the game on a P4 HT system running Windows XP x86. Recently I upgraded my system and am now running Windows XP x64. The problem did not occur on my previous install, and does occur on this one... clean Stardock Central installs in both cases. The reason I'm suggesting that this is related to x64, is because I have two other friends playing the game, both of whom are running x64 systems, and both of whom see the problem.
Not exactly a critical problem, but it is a bit annoying as I generally like to make heavy use of keyboard shortcuts.
-A