I can confirm this bug on HP Tablet PC TC4200 with 2.6.15-25-686, this model is similar hardware as in IBM ThinkPad X41.
The latest update for acpi-support 0.85 doesn't help either. I have also found a strange issue that the Suspend to RAM (Suspend) does not work without first doing a Suspend to Disk (Hibernate). -- [regression] Suspend [to-RAM and to-disk] is broken in 2.6.15-25.43 https://launchpad.net/bugs/50031 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs