i had a similar problem, i had a share set up on my windows xp pro computer and i could play some video but most of the time it just went to the mail menu.
scince then i have upgraded to windows 7 and have a share set up and i have not 1 single problem.
all i can say is try remaking the shares. (note: i made the OSD it's own profile on my pc.)
Unlikely to be the issue/solution, since:
1) The shares work fine under Arizona - it only fails under OSDng. Note: in other correspondence between myself and Greyback, he has expressed wonder/doubt about why this should be so, since the networking code should be the same between Arizona and OSDng. Still, it seems to be the case. When I get a chance, I will do some more testing.
2) The shares work fine under every other OS - all of my Windows, Mac, Linux, etc boxes can access the shares just fine.