Cross browser Vertical Menu Fix

Hi Guys,

I am having issues with the submenu in IE7 and Firefox 3.5.9.
By default the submenu in IE7 shifts to the right but is fine in firefox. When I apply this code it fixes the IE7 issue but then shifts the firefox.

ul.rMenu-ver li {
position:absolute;
margin-top:-1px;
margin-right:0px;
margin-bottom:0px
margin-left:-70px
}

Any help would be appreciated!

Thanks