I would like to fix it ASAP.
Thanks a lot for your help.
I'll just cut and paste the answer below:
In the campaign view of your account, just select the checkbox next to each of the blank Ad Groups in question, and hit the 'Delete' button just above.
Then select the "Show only active Ad Groups' option near the top-left of the page, and you'll see them no more.
Wow! Two posts for one effort.
Bonus! ;)
AWA
This is not to say, however, that it didn't happen to you.
But if it did occur, we'd certainly want to know about it! So if you're certain that you didn't change your end date (or that no one else with access to the account may have done so), then I hope you'll write to AdWords support explaining what happened, and when.
You can bet we'll take a look into it!
Thanks.
AWA