Intruder prg and zen problem

Hello Ken,
We understand how something like this can really try your patience.
Thank you for the detail information. We request you to reset your browser and check whether there is any other unknow application have been installed in your pc in control panel and uninstall it from your pc. Also run a complete scan in your pc.
Please feel free to contact us for any further assistance. Thank you.

Whenever I seek a site via my browser, once I get it, it cuts out and another prg.intrudes over it such as Express Player or some other advertisement trhingy. If I click it out, I then have to  start all over again at the site address I want, and I get thru and then can proceed. I also get a warning from AVG about that and allow the threat's removal, which happens. But if later I go to another site, it all happens again. I do remember, only once, in that warning, accidently clicking on "allow" which since then has/maybe caused the problem. Is there an "allow" vault" somewhere in my computer from which I can now exclude this item/virus? I have AVG security, AVG PC tune-up, and Zen except with Zenn it always tells me there is no plugin on my default browser. How can that be fixed as well? I've run all three often but this situation never changes. Any ideas to solve it all?

Hello Ken,
We understand how something like this can really try your patience.
Thank you for the detail information. We request you to reset your browser and check whether there is any other unknow application have been installed in your pc in control panel and uninstall it from your pc. Also run a complete scan in your pc.
Please feel free to contact us for any further assistance. Thank you.