invalid system disk

[AxshunJaxun]

Another long shot you could try before choosing to do the recovery, would be a Hard Reset. 

1. Shutdown

2. Remove the battery and power cord

3. Press and hold the Power button for about 10 seconds to drain all of the residual electricity from the computer, giving it a clean boot state. 

4. Put the battery and power cord back in and power on. See if Windows will load normally.

Were you booting to the USB drive or was it just a regular personal files and folders drive that was left in from the previous use of the computer?

(Sometimes USB drives are used in lieu of Windows disc, to boot from.) Were you booting from the flash drive? If so, do you know what your boot order is set to in BIOS? Could it still be set to boot first from the flash drive?

[jacquesroman]

I have a Pavilion p6347c with Windows 7 and had the same problem.  Here's what I did to launch Windows:

1.  Control-Alt-Delete

2.  When system reboots, hit the ESC key and it will display the available drives.

3.  With your up/down arrow select the first disc (has a bunch of letters and number)

4.  Hit return and you should be able to launch Windows.

Still haven't figured out how this can be fixed, because I have to do this every time I restart my computer.  Something to do with the BIOS.  If someone knows the answer, please advise.  Thanks.

[jacquesroman]

Had the same problem and rebooted.  Hit F10 repeatedly to go into BIOS, then, when in BIOS, hit F5 to restore system defaults, and F10 to save and exit.  That did it for me and fixed it.  I am running Windows 7 on HP Pavilion.  Good luck.  Hope it works for you.  Cheers.