Jquery Menu CSS issue in IE

Using:

Advanced Taxonomy Blocks 6.x-3.3
Jquery Menu 6.x-3.3

I configured a menu in a block. All worked well except in IE (6,7,8):
- click on 'plus' sign to expand menu to show children
- Jquery effect slides the menu down to reveal the children
- children disappear

Eventually removed the following css from my style sheet which fixed the problem:

ol, ul, dl {
  position: relative;
  }