As many people are aware, Sins and its various expansions have a nasty habit of minidumping once total memory usage exceeds 2GiB, which happens frequently with various combinations of mods and high detail graphics settings.
Someone at techpowerup (FordGT90Concept) created a utility to patch executable files to make them largeaddressaware (which is to say able to address more than 2GiB of memory) and a seperate forum post there indicates some success with Sins in particular. I haven't seen a link here yet, if one already exists please feel free to delete this thread. Given the frequency of memrelated minidumps, and the constraints it places upon mods and settings though this is certainly worth a large scale try.
This is essentially identical to the various fixes which have appeared for Supreme Commander (not expansion, which had the fix integrated), Fallout3, Sid Meier's Railroads, Oblivion, and various other games.
Caveats before link:
i) If you only have 2Gb of physical memory, stop reading, since this doesn't apply. 3GB plus is strongly recommended - you need to actually leave some valid memory addresses free for the operating system to work in.
ii) If you have a 32bit operating system, additional steps are required to see any benefit which I don't propose to explain here since it goes beyond simple file patching into tinkering with the mechanics of the Operating System, which is a far more hairy proposition for most people.
iii) Make a BACKUP COPY of any file you patch. While the patcher can reverse its change (which is toggling a single bit in the program header) there is always the potential for something to go horribly wrong, and a backup is your guarantee against such events.
iv) I have no idea how this will interact with the games internal checksum, it affects nothing in the program mechanics and none of the game data beyond allowing it access to more than 2GB of memory space.
v) Own Risk, etc etc, backups AGAIN, no responsibility if your copy of sins turns into Hello Kitty island adventure,
(NB - Remember you have to patch the exe you're actually playing. Suggest you backup "Sins of a Solar Empire.exe", "Sins of a Solar Empire Entrenchment.exe" and "Sins of a Solar Empire Diplomacy.exe", patch all three then play as normal.)
MAKE BACKUPS AND RESTORE THEM WHEN A PATCH IS RELEASED TO PREVENT WEIRD UPDATE ERRORS. REMEMBER SHOULD THIS WORK IT WILL BE NECESSARY TO REPEAT AFTER EVERY PATCH. Excuse the caps, but backups are important!
The link which follows has fairly clear instructions. I suggest you read the thread in its entirety, it isn't overly long and contains more technical details for those so inclined. Please post with results!
http://www.techpowerup.com/forums/showthread.php?t=112556