How can I regain Powershare USB control on a Alienware PC?

I have an Alienware Area 51 R5 PC. Recently I was having boot problems. There were indications that there was a problem in the BIOS (flash not initialised, or something). diagnostics ran, and I restored defaults in the BIOS. Eventually I solved the problem by booting into safe mode (which worked) then rebooting normally. Success. Now the powershare USB sockets switch off when I shut down the PC. I went back into the BIOS to re-enable USB powershare (as I had to do when I bought the PC), but the option isn’t there. I’ve upgraded the BIOS to the latest version, to no avail. The option to enable powershare simply isn’t there. Dell are no help. They just want me to re-install the OS, when my issue is in the BIOS. I don’t see how that would help. Any ideas, anyone? Thanks for reading.