Hi All, I have HP ProBook 6540b notebook. I have upgraded its bios and now it has started giving errors. 1. It gives checksum erroe CMOS reset(502), but now it doesn't come up with this error anymore as I have reset system configuring to default. 2. There is no display if system powered on while the hard drive is installed. 3. The system boots ot bios only when there is no hard drive and searches for drive. As there is no drive, it comes with erro"non-system disk or disk error" 4. System boots to windows when the hard drive is attached via ubs. 5. System boots with DVD when windows CD installed in it. 6. When I restore the bios to default settings, upon restart system ask for " the following configuration change was requested to this computer's truted platform module(TPM): clear the TPM= F1-accept, F2-reject. Now, please anyone help me how to make system configuration change so that it may recognise the hard disk. Or is there any problem with the bios installed??