Hi,
Had the same problem, it is linked to buggy HP software (the WBEM part I guess) not a hardware problem here.
I posted my solution on HP forum : http://h30499.www3.hp.com/t5/ProLiant-Servers-ML-DL-SL/ESXi-5-0-Hardware-Status-shown-as-Warning-but-no-all-Disks-and/m-p/5974573/highlight/false
Hope this helps.
Regards.