In SBS 2003 one User Account Can't Save "The disk you were saving to or the disk used for temporary files is full" error

I'm working in an SBS 2003 server enviornment.   Suddenly, one of my users can no longer save to the shared drive on the server and began getting the error: "The disk you were saving to or the disk used for temporary files is full. Free some space on this disk and try again. Or save to a different disk"  I logged in to the server as administrator, and within the user's account in the "Server Management Console" I accessed the user's account, and within the "Exchange General" tab I went into the "storage limits" sub window and unchecked the "use mailbox storage defaults."  I assume this only deals with email, so I went into SBS 2003 help and it indicated to modify user storage quotas I would have to right click on the volume that the user was saving to, select properties, and then I would see a "Quota" tab.  There is no such tab in the properties window, and there is nothing even resembling it.  How the heck can I change the user's storage quota? I assume that is the problem, since this only affects one user, and no matter which computer terminal she logs in from, she gets this error