Dropdown menu disappears before cursor reaches next submenu tab. Help

I am having an issue with my main menu on a website I am building. I lay my cursor on the a menu tab to have the tabs below it appear. I start down the tab with my cursor and the tab will disappear before I get to the next menu tab. It appears to do this on different tabs. It doesn’t to it all the time…usually when I am moving the cursor slower.

I thought this might happen because I had a second invisible tab menu below. To get rid of the default pages from that menu, I had to create a second menu and leave that menu empty in the admin section. I figured out how to get rid of the second menu in the the core.php and header.php though and I still have the tab disappearing issue.

Can someone please give a look? The website is http://www.jobsarchitecture.com.

The problem, seems to happen on firefox and safari on my mac. Probably in IE as well