Submenu is disappearing

I have just installed rtpanel but both in IE and Opera the submenu is disappering. When I Put the mouse over the menu, the submenu is showing, but as soon as I point the mouse on the submenu the submenu is disappearing....? look at

Hi dortebp,
I have checked your site on my end and it renders fine on IE and opera without any issues. Can you specify the version of your browsers?

I made some changes ind style.css and then it worked.
But before that it didnt work - and I have opera 11.61 and IE 8.0.
And it didnt work on my husband imac either.
So I think you have a problem.
It was a small line of space between the menu and the submenu that caused it.
When you move the cursor from the menu and towards the submenu the submenu disappeared as soon as the cursor hit the small space inbetween.
Somewhere in style.css under submenu I changed -1 to 0 and the small space disappeared and then it worked.