Cgminer not working

[AlPa]

I'm running cgminer on linux. I tried with 2 different pools (BitMinter and BTC Guild)

cgminer -o http://mint.bitminter.com:80    -u **** -p *** --auto-gpu --auto-fan --temp-target 70
cgminer -o eu-stratum.btcguild.com:3333 -u **** -p *** --auto-gpu --auto-fan --temp-target 70

But I get many "GPU0: invalid nonce - HW error" messages
so no actual work is accepted by the pool:
A:0 R:0 HW:57 U:0.00/m

My HW configuration:
   Asus p7p55d-e
   Intel i5-760
   Radeon HD 5770

Fglrx driver version: 9.00.11

Fglrxinfo:
OpenGL vendor string: Advanced Micro Devices, Inc.
OpenGL renderer string: ATI Radeon HD 5700 Series
OpenGL version string: 4.2.11903 Compatibility Profile Context

BitMinter Client is working fine but i just can't get CgMiner to work

Any suggestions?