I checked the recent posts and didn't see one on a hang issue I ham havign with Sins of a Solar Empire. I have updated to the April 22,2009 version via impulse, and the same hang occurs, albeit slightly later in the game.
I have this on a Vista computer, the memory size is just below that required for the 64 bit version, and I have plenty of disk space.
When it hangs, there is a dull sound repeating while hanging, but nothing else in the game is the same when it hangs (not building anything new, not first pirate attack, nothing).
Any ideas?