Google has their own brand of toolbar that is very similar to Yahoo!’s. It offers other features on top of Pop-up blocking, and looks like the following:
The following icon is the Pop-up Blocker: 
To allow pop-ups to appear, merely click on the icon. You should now see the following: 
To turn the Pop-up Blocker back on, you can click the icon again to re-enable the Pop-up Blocker.
Note: If this is not sufficient to allow pop-up windows to appear, you may need to disable the Google Toolbar completely by following the approach below.
Right-click on the toolbar and a Drop-Down will appear with a listing of all of the Toolbars.
Uncheck the entry Google to disable the Google Toolbar. To re-enable the Google Toolbar, right-click again in the toolbar area and recheck Google.