Internet Explorer treats \uFDD0 up to \uFDEF as equal. e.g. '(= \uFDD0 \uFDD1)' returns true.
Therefore e.g. '(symbol? :whatever)', '(symbol? (keyword "whatever"))' and so on return true which obviously shouldn't happen.
Further on read-string does not correctly unmarshal keywords because of that issue.
Using pr-str on that unicode range returns ":" for all codes.
All other non IE Browsers I've tested (Firefox, Chrome/Chromium, Opera, iOS BRowser, etc...) do not expose this problem and work as expected.
Clojurescript HEAD, tested ond IE7 and IE8