Application clashes with IE5

I have an accounts consolidation/reporting application (Hyperion Enterprise 4.6XA)that fails to run (I get a Dr Watson error)after I installed IE5. If I go back to IE4 it works perfectly. Hyperion say I have to upgrade to version 4.7 but surely there must be a way round this. Can any body help or suggest a solution? I want to have IE5!