I've been having the same problem. When i search by a zipcode, it gives me a list of caches, but when you click on the map it icon, the map pops up fine, but the "requesting geocaches" comes up and thats it. The caches never show up. Hope they fix this one soon. I like to use the map to see the caches near where I am heading.
I am using IE 7.0 also.