Modifying dynamic_sidebar() output – help!

I’ve got my sidebar set to use dynamic_sidebar('primary-widget-area'), and the problem is that it make a <ul> inside of a <ul>. I’d like to remove the inner tags that are generating the <ul> inside…what function is that inside of? And where is it?

I know this must be a quick answer but I’ve been looking for a few hours and I’m stumped.

Cheers