Cant Delete Sidebars

I have created some sidebars. Some of them I have had to delete, and they have been deleted without problem. Others however, no matter how many times I click delete, do not delete. Unable to delete them, I have tried to use them on some of my pages, but I have noticed that every time I click “Update” on a page that uses one of the un-deletable sidebars, the sidebar selection reverts to default and the sidebar does not display. I have to go back to the page, select the faulty sidebar again, and click update again to finally get the content to display. Any ideas why only some of the sidebars are having this problem? In case it makes any difference, the sidebars in question have been titled: “Server & Support”, “Service & Support – Customer Service”, and “Service & Support – Support Docs”