"Ok Bob, you're hired. Normally we'd send you a computer and all the other equipment you need, but our vendor communications are all fucked up. So we're going to send you the check we would have sent them, you deposit it, then you order the equipment from them. Plus that way your name is officially on the purchase and you own the equipment after 15 weeks! Why don't we just send the check to the vendor? What, are you calling me a scammer? How dare you!"

The scam is that they are secretly the vendor and they never send you the computer equipment that you buy with your own money. The money from the check they sent gets taken back by the bank because it's fake.