USB share and switch circuit
If you look at the datasheet of TS3USB30E that you're using, it only supports 3 V to 4.3 V for its own power supply (Vcc). So not only is connecting the VBUS'es of two computers together a bad idea (as @jippie noted), but you'll all supply 5V to your TS3's Vcc via Vdd (on your schematic).

I suspect they've spec'd the TS3 that way so that you can power it with a diode drop from 5V via diode ORing from two sources. Alas there's not much in the way of suggested application info in that datasheet.