Yes there is. But you have to search among the same sites as warez would be found on. Also, some free hosts have better banned scripts so that you don't come by problems such as yours. I believe netfirms.com does.
Doesn't tripod have an embedded ad option also? I'm pretty sure they do. If you change your ad type from the frames ad option to the popup option, that should do the trick.
Then if you made a 0 percent frame for the top of your site so the site address stays the same in the address bar even when you switch pages then you should only get one popup on the first entry to your page and you wouldn't be violating their tos. :webdev: