I've got a weird problem on one of my client's servers: A Windows SharePoint Services 3.0 site that has lost the option to add or remove users. Normally when you go into Site Actions > Site Settings > People and Groups, you can click on the Actions menu to add or remove users. Those options are no longer there. The only options that appear on the Actions menu are Email Users and Call/Message Selected Users. I'm logged on to the server as a domain administrator, which has Full Control permission in the SharePoint site. I was first alerted to the fact there was a problem a few days ago when a user reported they no longer had permission to upload files to the site. There have been no changes to this server in months - it hasn't even been touched. Any suggestions on how I should go about getting to the bottom of this? I only know the basics of SharePoint administration.