After loading a module with

:l Module

you can't use the Prelude functions unqualified, you just get things like

<interactive>:1: Variable not in scope: `show'

I am pretty sure that this worked some days ago, and I was using the same version then.

I feel totally confused. Has this happened to anyone else?

Yes, for some modules it happens for others it doesn't. Kind of strange. SuSE 7.3 rpms here, v. 5.02.2 J.A.