Vista - problem accessing folders

Not sure exactly whats wrong. When I first set up Vista X64 I told it to share everything with everyone on the network assuming that way I could access any folder from either computer on our home network.

Anyway when I'm on the main computer and click on Documents it opens and I see files and several folder including My Music Pictures and videos. I can open files that are listed but when I try to open say My Pictures I get the following mssg:

"F:\users\(myname)\My Pictures is not accessable.

Access is denied"

If I right click the folder and bring up properties under sharing it says:

"Network File and Folder Sharing
My Pictures
Not Shared"

and if I go to the security tab under the list of groups I have 4 entries:
Everyone
System
myname(my name-pc\myname)
Adminstraitors (myname-pc\Administraitors)

All are marked as full control but when I click edit to change permissions and highlight say "everyone" and click the OKAY button I once again get the mssg:

"F:\users\(myname)\My Pictures is not accessable.

Access is denied"

Anyway I'm going to do a sysrestore but could use some help/advice as to whats wrong

Have you tried to create the shares in the sharing centre under networks?
If you are trying to share from different computers be sure that the passwords are correct.
Try turning off the firewall (Purley for diagnostics not forgetting to turn it back on).