XP Pro SP2, FAT32, admin rights.
In Explorer, if I right click on the root drive (eg C or D) and select
"sharing and security", the sharing dialog box appears and I can share
/ unshare the root drive.
When I right click on a subfolder and select "sharing and security",
the sharing dialog box DOES NOT appear. Nothing happens, nada, nix,
zip, zero.

I also have a subfolder that I shared when I installed XP about 12
months ago. I now cannot unshare this folder, the sharing dialog box
refuses to appear.

My network works fine. I can see other machines on the network and copy
files to / from them. I have run the network wizard to reset file
sharing, no go. Simple File Sharing is ticked. The share service is
running (which it must be if I can share the root).

Can someone please help? Are there any command lines or third party
products / tweaks I can use? I'm getting desperate and short of  new
install, I cannot see anyway around this problem.

Note - the same problem also happens for the "Properties" of a folder.
I can get the Properties dialog box to appear for the root dir but not
for any of the subfolders.
I suspect the two problems are related and if I can fix one then maybe
the other will go away....