Cannot log into yahoo mail beta using firefox? error message about some scripts?

Question:i got the following error:

Yahoo! Mail beta experienced log in error:
name:ReferenceError
message:setupInit is not defined
lineNumber:640
and then an address to a yahoo file name

than okay that error and get another similar one about attachfoldernodes to folders not defined.

ive tried firefox 1.5 and the new version (2.0.04)

ive cleared cookies and cache?

anyone know the solution?

thanks

Answers:
Yahoo highly recommends internet explorer so firefox would not work with it