Hi Hozy,
I've managed to get Impulse to autoupdate itself, I now have version 3.11.333 (images:3.10.181)(Build 947). Currently Impulse is "Preparing download.." of Sins:Solar Empire update v1.12.042. Plus my HDD light is constantly lit so I'm guessing something's happening.
If you want to try what I did, it may or may not help resolve your issue. I basically uninstalled all current and previous versions of Microsoft .Net Framework Service. Went and got the latest Microsoft .NET Framework 3.5, and installed that. So far so good, now downloading 1.8%