1.Once a computer is loaded with a Linux based OS, any live-USB written from a Windows based computer does not work for the linux based computer anymore.
2.If the live-USB is written from a Linux based computer, it does work for Linux but does not work on Windows computer.
I do at least 6 or 7 installation every week (mix of win xp,7 ,ubuntu and Mint) and create boot stick either in linux or on windows and never had a problem? I always make sure to wipe my usb drive before trying to install as some bootloaders have a strange habit of hiding part of the mbr on the sticks or using a fake cd boot loader. So don't trust too much the usb "installation" software to do the job correctly, take the extra 5 minutes to recreate the partition table of the stick and format to fat32. (in win or linux)