Mark, Here we go ... Attached is a compound version against v2.6.28.4 of some hpet patches that I'd like to submit asap. Can you please apply this patch and test it on your machine. By chance I've found a machine wich also hangs with HZ_1000. And this patch fixes the problem on this machine. Regards, Andreas PS: Please boot with "hpet=verbose" to show the HPET registers (no additional debug parameter needed this time). -- Operating | Advanced Micro Devices GmbH System | Karl-Hammerschmidt-Str. 34, 85609 Dornach b. München, Germany Research | Geschäftsführer: Jochen Polster, Thomas M. McCoy, Giuliano Meroni Center | Sitz: Dornach, Gemeinde Aschheim, Landkreis München (OSRC) | Registergericht München, HRB Nr. 43632