I FOUND bug
i just tested witch works and since when doest until 4 in row from http://kernel.ubuntu.com/~kernel-ppa/mainline/
Confirm by installing kernels
No this bug using:
[DIR] v188.8.131.52-natty/ 18-Feb-2011 11:34 - http://kernel.ubuntu.com/~kernel-ppa/mainline/v184.108.40.206-natty/
This bug starts in every next kernel since:
[DIR] v2.6.37-natty/ 05-Jan-2011 11:23 - http://kernel.ubuntu.com/~kernel-ppa/mainline/v2.6.37-natty/
take files starting with linux-image-*** ending with *** your architecture i386.deb or amd64.deb
then install them and restart in each kernel.
For my Emachines E525 this is how i wrote.