Overflow Woe
Scrollbars when you don't want them? The overflow property is likely your bugbear.
Often when I've done something special with the Plone searchbox, things go haywire in IE:
When text is entered into the searchbox and livesearch kicks in, there's no room for the results to display in IE. I fixed this by adjusting the overflow property on #portal-searchbox:
#portal-searchbox {
overflow: visible !important;
}
Yeah, the !important is bad style. This was an old theme without an IE-specific stylesheet.