Find the Tool Bar with Pop-up Blocker. Usually it will have a "Stop" sign or "Don't" symbol and state how many pop-ups have been blocked. Examples include Starbuster, Google Tool Bar, Dogpile Tool Bar, Yahoo Tool Bar, etc.
A. Here is what the Google Tool Bar looks like:

The Blocked Pages Indicator looks like:

B. Dogpile's Tool Bar looks like:

The Blocked Pages Indicator looks like:

C. Yahoo's Tool Bar looks like:

and the Blocked Pages Indicator looks like:
Locate the Options or Preferences or Settings for the toolbar's Popup Blocker.
A. Google Tool Bar settings are found by clicking on the Options Button:
B. Dogpile's Tool Bar popup settings are found by clicking on the Down Arrow on below part of the tool bar:
C. Yahoo's Tool Bar popup settings are found by clicking on the Down Arrow on the below part of the tool bar:
Turn off the Blocker.
A. For Google Tool Bar, under the Browsing Tab, Uncheck the Popup Blocker then press the OK Button:
After doing so, the Popup Blocker Icon (
) will disappear from the Google Tool Bar, indicating that blocking is now turned off.
B. For Dogpile's Tool Bar, after clicking the down arrow (
), click the Turn Off Popup Blocker link as below:
After doing so you should see the blocker change to Blocking off:
indicating that blocking is now off.
C. For Yahoo's Tool Bar, after clicking the down arrow (
) , Uncheck Enable Pop-up Blocker:
After doing so, the Popup Indicator will change to:
indicating that popup blocking is now off.