[Zurvan]

Having worked in a Customer Service department for a major technology corporation, and handling rebates, I can tell you that this is absolutely illegal, and if they have not stopped payment on the cheque & cash it, they will sue you.

And it won't cost them much, because they have lawyers on staff. They'll send you a letter telling you you will be sued, and that is typically enough to convince you to pay it back (it would convince me). And if they win the case, they can hit you for court & legal fees as well as the $150.

As for the people who said that since they sent it after you returned it, so it's their fault - typically rebates are handled by an outside service provider. The rebate would have been sent directly to them, and they would send a list to Toshiba of sales. Toshiba would approve them, and (eventually) the cheque gets sent. If you returned the computer in the middle of that process, it could have been approved already.