menu problems on ATA 3.5.3 and WP 3.1.2

I *also* am seeing problems of late, & I'm on an old version of Ata (v3.5.3) & of WP (v3.1.2)

(Drop down submenus disappear: the menu *might* display the first link of the list, but not others, intermittently, yet the area the rest of the drop down would occupy on the page is white. I'm on Mac 10.8, Firefox, while a friend has seen a similar problem today on a PC w/Firefox & Chrome, & IE apparently simply screws up the >> arrows indicating a sub menu.)

My friend that recommended WP & Ata several years ago, & helped me with some code tinkering & settings for the site had said that upgrades could cause things to break, & not to upgrade.

For this problem, she suggested I get a patch for v3.5.3, but I don't see where to find that.

Suggestions about upgrading Ata & WP, or about the patch, or about what to fix that's specifically causing the sub-menu prob?

(I post here because this MIGHT be consistent with upgrading to the newest Ata version.)

Thanks!!!
Ric