Click on the Icon in the upper left hand corner of Impulse and select Preferences, than click on 'Reset Data'.  Had the same problem and it cleared it up for me.

Most times this will fix minor Impulse problems.

I've found this solution and it's working for me.

1) When an update is required, don't bother to update.
(2) Close Impulse.
(3) Run Impulse manually as administrator
(4) Say "Yes, I really do want to run as administrator"
(5) If need be, enter your registration details.
(6) Auto-update will occur.
(7) Repeat steps (2) - (6) if need be.
(8) Run Impulse as your normal account (non-admin)
(9) If it prompts for "credentials" again because it thinks update failed, that's only because of leftover previous attempt, so enter your normal credentials (not admin), and it will indicate update *may have* failed, but close Impulse and re-open, and now no more complaints.

S J N if you have done all of the above without fixing the problem then the question comes to mind 'Was it working okay before?', if so have you made any changes to your computer that might be the cause of the problem?.

It might also help to know what OS you are running.

That's odd.  

I'm running Win 7 64 bit also.  Sounds like you may have to email support. 

That is what I am showing.

Thanks Philly and Cavan. I guess it did update. I still got an error message though. Thanks again.