You may need to enter the bios of the laptop.
Depending on the laptop you may also have limited bios options.
In any case find out the key, or combination of keys you need to press to enter the bios setup of the Vaio laptop.
The first option to look for is Enable detection of usb legacy device, make sure it is set to enabled.
You will then need to go to the boot order list of devices, if you have the option to select a usb device as a boot able device then set it to the number 1. in the booting list.
Save the new changes made in the bios before you exit it.
Providing you have used something like Rufus to create a boot able usb partition on the usb flash drive via a image file.
You should then be able to boot from the usb flash drive and begin the install of linux on the Vaio laptop Souflex.
Hope it helps you anyway, and your welcome.