DP 8.07 Audio driver shutdown and memory allocation issue?

[Blaremusic]

Hey there,
I could sure use some advice!
I am running DP 8.07 on a MacPro/Yosemite and an Apollo Quad (see all system details below) and audio keeps shutting down during playback/record ("Emergency Stop" dialogue appears, saying "The audio hardware's state changed while MAS was running"). The "Memory" light in the upper right side of the DP control bar is often solid red (despite having upgraded from 6 GB RAM to 24 GB RAM). (Sometimes this dialogue even appears when the machine has sat idle for a while). The "Performance" meter (above "Memory") still reads high, too. This, by the way, happens when I'm running as few as one instance of Kontact with, I dunno, Abbey Road drums loaded and no plug ins. (But also happens when I'm running as many as 18 plug ins, no virtual instruments)

The dialogue comes up, I re-set the audio system, and I'm good for maybe another 10 minutes.

UAD software is all up-to-date (though the UAD Control Panel says of FireWire "42% used by UAD" and "29% used by other devices" when there are no other FW devices connected.

I WAS using DP 8.07 in 32-bit mode to accommodate some old plug ins I rarely use, but found that this problem occurs in 32-bit or 64-bit mode.

(By the way, ProTools 10 now won't open at all!)

Any ideas would be very welcome!
Thanks,
Blair
********************************
MacPro (mid-2010)
2X 2.4 GHz Intel Xeon
24 GB RAM
Yosemite 10.10.5

Apollo Quad - UAD - 2
UAD 8.4.0 software

Digital Performer 8.07

[mikehalloran]

What is your buffer size?

[Blaremusic]

You mean "buffer size" in the DP Hardware Setup dialogue? It varies. 256 (or even 128) when I'm recording, or 2046 the rest of the time. Thing is, this problem happens no matter what the buffer size is set to...

(Thanks for replying, btw)

Blair