Not sure what to say as I am no tech of comp, but I have firefox for browser on Win7 and cattery has been fine for me. Albeit I do not have any cats currently in ( and will now be waiting till I hear any other success stories) but I was able to load it with milk just fine. Not sure if this information helps or not.
Kitty Cats Are Like Potato Chips, You Can Never Have Just One
Website Cattery issues
Kitty Cats Are Like Potato Chips, You Can Never Have Just One 
