PJH
Afrodrum
Happens to me too. They sound strange, like the completely new kind of glitch I never heard before in Sonar, loud, scratchy and nasty. Though it does not happen everyday, perhaps every other day.
Yes, that's exactly what I was getting.
Yes, me too at first. I found increasing my interface's buffers up a bit got rid of the crackling though. However as my project pressed on I also had to increase my read/write i/o buffers (hard disk) as well to avoid dropouts (not crackling... just engine dropouts).
Please read my following reply to JonD as it may be of use to you (I've been poking at alternate plans to fix my own issues).
JonD
Well, the Manchester update should be dropping any day. We'll know soon enough if they've found and corrected those issues. The great thing is, we can always roll back or stay put at a solid release.
I've been on Jamaica for awhile and it's been solid for me. No more experiencing weird behavior or the odd change here and there after updating every month (I'm on the prepaid annual plan).
It's been quite liberating, and has taught me an invaluable lesson on the virtue of being patient. I now plan to only update maybe twice a year, depending on where I'm at in my projects -- and, of course, which updates are most solid on my system.
And yes, I still enjoy the monthly release of new features, knowing I'll have them eventually. 
Yup... I am currently waiting for Manchester to be released to see if it fixes things on my system. I am an offline installer so I would prefer not to move backwards (it's a manual installation which overwrites the previous one which supposedly works but I am hesitant to do so because it MIGHT cause some oddities based on SOME reports).
Otherwise I will be trying Kingston and if that doesn't work maybe Jamaican Plains. I'm thinking Kingston would be the better choice because it seemed like a refinement of JP and there weren't any complaints (aside from the instrument updates which are separate and unrelated to the main Sonar APP).
Also... and I mentioned this in my other thread, what is happening on my system is my Performance Module is showing much higher than normal CPU usage across all cores and recently (because my project track count had grown as well as my "Comping" splits/edits) the HDD icon was redlining (which cause engine dropouts). That is why I increased my interface buffers (which reduces CPU) and read/write buffers (which reduces HDD dropouts).
I also started freezing tracks I wasn't screwing with anymore or recording into which Ive never had to do in the past.
I mention all this because perhaps it will help folks having these issues with Lexington muddle through until Manchester is released. As I said I think I'm going to wait for Manchester, test it and then if it doesn't correct these issues install Kingston.
Cheeeeeers!