system
9
A thing that is not backwards compatible just… uhm, sucks. It is not even full-featured in all versions of W7 (you can create HG just on HP/Pro/Ent/Ult, others can only join) - the fail gets epic here. And completely useless in mixed environment (XP, Vista).
Anyway, to get back to the track here: For a more useful diagnostics of what is actually blocked or not - browse to \computername\sharename (of course replace according to your setup) - does it work?