Well I've figured out a bit (but not much) more of what's going on. It turns out I've not explained it correctly. When I open skype, there are supposed to be two windows: the login window and the main GUI window (the one that you use to dial and so on, once you've logged in). If the system's working normally then the main window's there the whole time and the login window disappears once it's not needed any more. On my system, only the login window is ever visible. After entering my correct username and password, the login window disappears and skype seems to be running somewhere but nowhere that's visible. There are two reasons why I say it's running:
1) I use alt-tab to switch windows. When I do so there's a little display that pops up telling me what windows are available to switch to. It says skype's available, but when I try switching to it, I get nothing.
2) The command 'ps -ef' says skype is running.
Number 2) leads to a new issue altogether. 'ps -ef' claims that there are several instances of skype running at once. On another (normally running) system that I have, only one instance of skype is reported. But on this system that isn't working, I get several, like what's shown below, after only entering the skype command once.
Code:
UID PID PPID C STIME TTY TIME CMD
chad 4472 3350 0 12:27 pts/0 00:00:03 skype
chad 4473 4472 0 12:27 pts/0 00:00:00 skype
chad 4546 4473 0 12:33 pts/0 00:00:00 skype
chad 4547 4473 5 12:33 pts/0 00:00:00 skype
chad 4548 4473 0 12:33 pts/0 00:00:00 skype
chad 4550 4473 0 12:33 pts/0 00:00:00 skype
chad 4551 4473 0 12:33 pts/0 00:00:00 skype
chad 4552 4473 0 12:33 pts/0 00:00:00 skype
chad 4553 4473 0 12:33 pts/0 00:00:00 skype
I'm not sure yet what the meaning of this is.