Sounds like your browser is picking up faults in the code used to make the pages you are viewing.

You can turn off debugging messages in your browser.

In IE, click 'tools' then 'internet options' then 'advanced' then look in the section called 'browsing'. There will be a number of tick-boxes. you will see a couple called disable script debugging. tick both them boxes and click ok / apply to close the windows. Restart IE and the pop-up messages should be gone.