Sharing and removable drives

Hello, hopefully someone can answer this question as I've searched for an
answer everywhere.

I'm running Windows Vista x64 on an all wired network but what I can't
figure out is why a network share I set up on my Kingston USB drive
disappears after I reboot my PC. I also set up network shares on folders in
BestCrypt drives and they also disappear after a reboot. This seems to be
affecting removable drives only because on a fixed disk Windows keeps the
shares.
Some of my network settings: Network discovery ON, File sharing ON, Public
folder sharing OFF, Printer sharing OFF, Password protected sharing ON,
Media sharing OFF.

Thanks for any help.