After enabling HYPER-V role / Processor Execute Disable BIT server HANG during booting...

hi,

i have installed windows 2008r2 english (german regional settings) on IBM x-series 3650 server.
after this i have enabled the hyper-v role.
the server restarts without any problems...

then i tried to install a VM, but then i saw that i have forgotton to enable the PROCESSOR EXECUTE BIT to ENABLE

so i shutdown the server; changed the BIOS settings to PROCESSOR EXECUTE BIT to ENABLE
restart the server: --> the server is booting, after some secconds i see only a black screen and the server is HANGING...

if i change back the BIOS settings to: PROCECSSOR EXECUTE BIT to DISABLED
then the server starts fine... but i can't start a VM as i get the info: "...hyper-v service is not running..."

i also tried to install w2k8r2 SP1

so what can i do ???

thanks!