What does "Check the clock on your BIOS first, if the seconds are out but the time is correct, this the likelihood of the problem is being caused by the BIOS clock" mean? I don't understand what you are syncing the BIOS clock too and what does "if the seconds are out but the time is correct" mean. I get this error when I try to install Flash and I seem to have no Flash plugin now in Firefox. I still have one in IE.
What is the exact error you are getting?
Have you tried to run the offline installer from http://helpx.adobe.com/flash-player/kb/installation-problems-flash-player-windows.html#Ins tall_in_a_firewall_proxy_server_environment ?
If that still causes you an error please post your Windows version & edition.
P.S. if your Windows user account has administrative permissions, then you don't need to go into the BIOS to correct your clock; you can do it from withing Windows, either manually, or using Atomic Clock Sync.