As of this morning, I have the strangest problem I have ever had with my Mac. The problem is that I can't drag items. I can drag windows to move and resize them, I can drag scrollbar widgets to scroll, and I can click and drag to draw in Photoshop &c, but I cannot drag items. For instance, I cannot move files in the Finder, I cannot drag messages to move them to other mailboxes in Mail, I cannot drag songs to playlists in iTunes, I cannot drag links on pages in Safari (although I can drag bookmark bar items to move them), I cannot drag selected words inside TextEdit, and I cannot drag files to my FTP server in GoLive. When I try to drag, the system doesn't respond. Nothing freezes; the items just sit right where they are as if I weren't touching them. It is not a hardware problem; such dragging works neither with my trackpad nor my Apple Pro Mouse. Nor does my system need a restart; a restart did me no good. My system was working normally until the problem quietly and suddenly began about a half hour ago. I am using a PowerBook G4 400/512 and OS X 10.2.4. What in hell is going on?