Re: PC randomly freezing
Burn memtest to DVD and try that, some USB sticks are not supported for boot depending on some brands of mboards and sticks I believe, it is the only reason I found off top of google search as to why it wouldn't boot from the priority selection you made.
Happy new years to you aswell!
edit: Also something important for certain sticks/mboards:
Format USB stick with either FAT 16 or FAT32, NTFS is not supported.