[LAU] Intel-HDA sound issues

Hi All, I've got one of these pieces of crap in a reasonable enough laptop. When I start jack, with 17.4 ms latency (3p/b, realtime, unlock mem,priority 70) I get sound being very crackly from a "test" app -- zynaddsubfx. Note this is very much not normal behaviour before Hardy Heron (wife had a baby after then and didn't have much time until now) when under Gutsy, zyn, hydrogen, rosegarden and ardour all ran swimmingly together. On the messages from Jack I have: delay of 5034.000 usecs exceeds estimated spare time of 4993.000; restart ... delay of 5101.000 usecs exceeds estimated spare time of 4993.000; restart ... delay of 5101.000 usecs exceeds estimated spare time of 4993.000; restart ... delay of 5031.000 usecs exceeds estimated spare time of 4993.000; restart ... delay of 5031.000 usecs exceeds estimated spare time of 4993.000; restart ... delay of 5073.000 usecs exceesecond. I'm running 2.6.24-21-rt under ubuntu Hardy heron. Anyone got any ideas? Jonty