Mac, Audiofire 12, Ableton Input crackles.....

[analogcabin]

Hi.

I've been using Live since version 2 without a single buffer interface issue - ever.
Lately I've been getting random digital hash, crackles etc on input only. Add to that when I try & change buffer settings using the test tone 80% goodie it's really buggy. Sound drops out completely. Odd.

My current settings are (and always have been):
*24/44.1
*128 Buffer
*Echo Audiofire 12
*Mac Pro
*Live (8.3.4)

Playback is fine. Recording In is the issue. More buffer makes it worse it seems. Very confused.
Anyone have any suggestions for a plan of how to troubleshoot?

Many Thanks.