playback crackling

Mac OS High Sierra (late 2011 MacBook Pro, so quite old)
Audacity 2.4.1
Working perfectly for last five+years using older Audacity version, then overnight getting crackling with message “Recorded audio was lost at the labelled locations. Possible causes:Other applications are competing with Audacity for processor time. You are saving directly to a slow external storage device”. Happens using Samson external mike or inbuilt mike, and also when playing back imported audio track recorded on another device. Also happens when recording input volume is actually moved to zero. Crackling stays on track when mp3 exported. Tried deleting old and downloading new Audacity version but still exactly the same. CPU usage looks fine. Using directory ‘Documents/audacity session data/SessionData’ and says free space 322.2 GB. Hope you can help.

Try resetting Audacity’s preferences as explained here:

– Bill

Many thanks for your time. Your solution has worked perfectly.