This issue has been discussed previously (see:
http://forum.virtuemart.net/index.php?topic=97482.msg323135).
Within that thread 2 suggestions were made, the first being:
To fix it need change in vm2admin.js (in administrator\components\com_virtuemart\assets\js
from list += '<li style="width:'+tabswidth+'%"><span>'+ $(this).attr('title')+'<span></li>' ;
to list += '<li style="width:'+tabswidth+'%"><span>'+ $(this).attr('title')+'</span></li>' ;
around Line 14, i.e. simply add a "/" before "span"
This simple addition appears to resolve the tab problem in IE.
However, the 2nd suggestion to "correct look in ie8" has also been tried but it does not appear necessary and also appears to cause issues in other browsers such as Firefox.
So, just try adding the "/" and you may find the tabs will work in IE - however the full content had always been available by scrolling down the page.