Hello, I was opening a sequencer (Rosegarden, to be specific), and usually it works fine, but this time it seemed to play this ever-looping low piano note. Exiting doesn't help, etc. and I am really irritated right now. This note has just been playing over and over again for the last... 1/2 an hour? Is there some way in Linux that I can reset my sound card or at least reset the MIDI? I really, really need to stop this note ;). I'm using ALSA with a Creative Audigy 2 if that matters. Thanks in advance!

IIRC, unloading and reloading the sound drivers should do it. You can also send a MIDI "system reset" message, but if it's a note playing repeatedly, as opposed to a note playing continuously, the problem's more serious than just a "stuck on".

If there is one, I didn't find it ;).

you could try unloading the sound modules.