How to Fix Mac App Store "Error 100"?

I just downloaded Mac OS X 10.6.6 and launched the Mac App Store to get out some apps. When trying to download an app I was hit with this error message:

Then, how to fix Mac app store error "100"?

The cause seems to be lying in the fact that in the first minutes the Mac App Store went live and Apple let users log in with Apple IDs, they didn't include the updated Terms and Conditions to accept before start using the Store. Thus many users logged in without accepting the Terms and were unable to download apps because they were stuck in some sort of "limbo".

Here's how you can fix error "100" in Mac app store:
- Sign out from the Mac App Store. You can do it by accessing the "Quick Links" section in the Mac App Store homepage and clicking on "Account". Sign out.

- Quit the Mac App Store app.
- Log out from your computer; log in again.
- Open the Mac App Store, sign in with your Apple ID, try to download a free app and accept the Terms and Conditions when asked. After that, the download should start.
- If a logout doesn't fix the issue, restart your Mac instead. We're hearing that a reboot fixed the problem for many users.

Done! Now you can fix the Mac app store error "100". Enjoy the Mac App Store!

Related Tutorials:
How to Download Mac App Store?
Why Need to Pay for free Apps on Mac App Store?
Top 6 Must-Have Apps in Mac App Store