App Store opens unDock Lite product page seemingly randomly
Is there any mention of the app or the page in ~/Library/Cookies/com.apple.appstore.plist? At least one other AskDifferent user had trouble with this file and solved the problem by deleting it - maybe that should be the last resort though.

You can also enable "debug mode" in the Mac App Store by doing defaults write com.apple.appstore ShowDebugMenu -boolean YES - when you have done that you will see a new menu:



I would try Clear Cookies first, and if that doesn't help, Reset Application.