Both could be related or not related at all.
1) Use the lookup at www.stardock.com/support to get your serial number emailed to you. This will verify that you are using the correct email address and also allow you to try and manually register the product. Try manually registering the product and/or verifying that the registration number is showing the correct number in Impulse.
2) Please make sure that you don't have any anti-virus or spyware apps that are mistakenly blocking Impulse.
Do you have any other products installed through Impulse, or is this the only one?
How was Sins installed? Was it through Impulse or as a stand alone install (ie: boxed version)?
What version of Windows are you running, and what version of Impulse do you have installed?
I'm about to leave town, but I will alert others to watch for your response.