File sharing problems in Vista Home Premium

I can't get folder sharing to work at all on my computer. I have tried
everything I can find on the internet, but nobody seems to have the same
problem as me.
When I try to turn public folder sharing on, I get the message "The RPC
server is unavailable."
If I try to put the folder I want to share in my public folder, I get the
message "You need permission to perform this action."
I am the only user on this computer and I don't see anything wrong with the
administration stuff. I've posted this once in here but never got a reply,
probably because nobody else knew what to do either.
I have to say, compared to XP, Vista is a unbelievable pain in the ass for
almost everything. If Mac had a tablet, I would've gotten one.
Any clue what I can do to fix this problem?