I have received this message: - The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem. I clicked the blue print for help to solve it and I gather the first instruction is to restart Firefox. I have no idea what that means - Do I click the wee cross top right to close it and then click the Firefox wee sign to open it again. I tried that but get the message.