Windows Anytime Upgrade unsuccessful

I tried to upgrade my Windows 7 Home Premium to Professional but the upgrade failed and here's the error in the upgrade.log file: DoTransmogrify failed due to error 0x80070002

I did a quick search and afterwards disabled UAC as well as my Anti Virus. UAC asked me to restart the computer so I did. However, to my surprise, when the computer was booting, the upgrade process continued and finished successfully (I'm using Professional now). So I want to know why did this happen? Originally it said unsuccessful then exited yet when I restarted the computer everything continued just fine. Will I run into any problem in the future?

When I googled the error code I found this link:

You receive a "0x80070002" or "0x80070003" error code after you download an update from Windows Update, from Microsoft Update, or from Windows Server Update Services

You can click the Fix the problem automatically link to have Microsoft try and fix it.