Vista and XP network filesharing

I recently bought a new PC for the front room as a media centre.
It runs Vista Home Premium

It seems to conect fine to my XP machine upstairs.
The vista machine conects by wifi to the router the XP machine conects
via ethernet.

On the vista machine i can see the directories i have specified to
share;

example ;

Photos

Music

shareddocs


problem is when i try to enter say Photos (a large directory) it thinks
for a while then hangs.

same for Music

the shareddocs directory was empty - so i put a simple text file in
there.
this i could access ! so i put 1 picture in there about 4MB - no luck
hangs again - with a message saying could not connect might need to
contact the other computers system admin.....


any ideas -- appears to be related to file size - but sure 1 photo
should not be too much ??? my connection is 54MB and "very good"


--
lupgop2000

i really am stuck here !!! played around a bit more and can occasionally
open text files (held on the XP machine) on the vista maching. - also i
can drag and drop files from the Vista machinr onto the XP machine. I
still cant open files in shared directories on the vista machine (except
for the occasional text file?) I turned off the firewalls on both
machines. could the firewall on the router cause problems??? - what
about windows defender ? it's like i can see everything but there is
some conflict - my conection to the router is good - internet actually
fast.... and siginal says excellent ???


--
lupgop2000