I don't see why the router would affect this.... :icon_scra .
Could you try disabling your windows firewall, and any popup blockers you may have.
Make sure you check your toolbars as well, because some contain popup blockers.
It might be worth uninstalling Mozilla, clearing the temp files and then reinstalling it just to see if it works on that.
- Do you have any other machines/laptops in your house that you can test on the wireless network so we can identify if it is the PC or router?