Ok here is something for you to try to see if something funny is going on with the packets being sent.
Go here and download wireshark 1.0.8. Install it. Accept all the defaults. Make sure you run the installer by right-clicking and choosing "Run As Administrator"
Now when you are getting ready to start a session of DG and have your IM running and all that crap...
Run wireshark. Make sure you start wireshark by right-clicking and choosing "Run As Administrator".
Click the menu item Capture -> Options
In the new window, select your NIC from the "Interface" dropdown list.
Click Start
Now run DG and have it do its thing where it fubars your internet.
Quit DG and go back to wireshark
click Capture -> Stop
If you get an error that it did not collect any data, then you may need to repeat this process and before clicking Start, find the checkbox on the Options window for "Promiscuous Mode" and uncheck it.
Once you've successfully captured some output, you can click Save to save the output to a file for analysis.
Now you have 2 choices - try to analyze the packets yourself using the Wireshark interface. Maybe it will tell you something you can understand. Or you can PM me and I'll give you my email address and you can email it to me and I'll look. It might be helpful for you to do the same thing on a computer that is working properly so we can compare the 2 and see if anything is different. I'll warn you in advance - the file contains all your network traffic while it was capturing. If DG does not encrypt the login info when logging in, then your Impulse password will be sitting in the file. Same thing for your IM app if you login while capturing. If you send the file to me, I suggest you login to IM before capturing and if you don't want to trust me, then change your Impulse password to something temporary before doing this test and change it back afterwards.
good luck