Bio keep rebooting in my Dell E6500

You might try a system restore from safe mode command prompt.

Start the System Restore tool at a command prompt

1.Restart your computer, and then press F8 during the initial startup and select from the options: Safe Mode with a command prompt.

2.Log on to your computer with an administrator account or with an account that has administrator credentials if needed.

3.Type the following command at a command prompt,

%systemroot%\system32\restore\rstrui.exe

and then press ENTER

4.Follow the instructions that appear on the screen to restore your computer to an earlier state.

Try tapping F8 at bootup and select "Last Known Good Configuration" then Enter. If this doesn't work, then you might try system file checker. Go to the safe mode command prompt and type sfc /scannow. Note: space between c and /

You may be asked for the Windows CD, if asked insert it.