"You have to delete the partition, then recreate it then format the partition. "
It was exactly what I've done.
"I still say check the BIOS settings carefully"
Believe me I have. Besides, I'm writing this on the PC with the "problem" on a Ubuntu Persistent USB and it reports 1.5Gb.
"I have some thoughts, not good ones but I will wait to see what others have to say."
Well... Nothing else to say :)
Please check this. It may have nothing to do with this, but it's some info:
The topic was mine too.
Thanks again to all.