More than likely something is interfering with your connection such as antivirus/antispyware/firewall software. I would suggest adding an exclusion for Impulse.exe within these programs.
As sort of a workaround, you can download the game installer/archive files from here http://anywhere.impulsedriven.com/Default.aspx when you sign in with your Stardock.net account. This will download full copies of the games. To get just the updates you will need Impulse working.
To help accomplish this, if you can send us (email@example.com) your Impulse error log and your startup/dxdiag information we can take a look at your system configuration to see what might be giving you trouble. Information on how to gather these files can be found here: http://forums.stardock.com/341573