1. Without the name of the app or update any ideas are going to be bad guesses.
2. I see on google lots of open discussions about installer GUI failures.
Bob
I go to download an update, and it starts downloading fine, but as soon as the bar graph starts to indicate download speed, a popup box comes up stating that installer GUI failed to initialize. Regardless of whether I click OK or not, the software fails to install.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic