Sudden ocean of static/hiss

[lamiki]

I'm not really any good at anything DAW-related except composing, but after being around Performer/DP for 17 years it still maddens me that I can close my setup then return exactly where/how I left off only to find a work-stopping glitch. Today my project's audio tracks are floating distantly in an ocean of static/hiss, the static similar to that of a buzzing guitar cord. The audio monitor shows the noise registering on all inputs of my 828 at -24 db.

I have a late-model Mac Mini, MachFive3 installed (not using it yet), an MTP AV, several classic Roland synths, and a Fatar piano controller. All indicator lights are firing as they should when I press a Fatar key to trigger a sound on a particular MIDI track, though the sound is muffled by the static/hiss.

There are no problems when listening to my iTunes library through the 828; but should I then open DP, I hear the static/hiss, and a high-pitched staccato tone accompanying it. Please note that the high-pitched tone isn't there when DP is running alone.

Any suggestions? Thanks. Hope everyone's work is going well.