drive mappings disconnect

my computer is on a windows domain. i have mapped network shares drive letters. It worked for awhile and now I am seeing that whenever I reboot my computer the drive map letter has red x. I can click on it and reestablish the connection but it always goes red when I reboot. what can I do?

if I map the drives as "administrator" won't those drives only show up for the user "administrator" only?

thanks for the tidbit. Good information but it did not work