You probably don't have one then. A hub is a device that plugs into a USB port and has more ports that you can plugs more USB devices into. Basically lets you plug 4+ USB things into one USB port. They normally work fine, but can cause problems every once in a while.
The other thing to try is make sure your motherboard drivers are all up to date. If you have a name brand PC (Dell, HP, etc.), go to their website and download all the latest drivers, especially the newest BIOS and anything about USB.
When the computer bluescreens it has a bunch of info, like an error code ("***STOP: 0x" then some numbers), and usually a description. That might help figure out what is wrong too.