Sorry to sound rude but did you try updating the motherboard bios - you didn't say if you tried that, only that you'd cleared the BIOS.
If paypal have done that to you and you used a cc then id do a chargeback then phone paypal letting them know your dissatisfaction in the matter and sort it out there and then, they have no legal right to do this.
There is an option to open a dispute through paypal for a return. They normally respond to that.
I was in a similar situation, Emailed them constantly for about a week then just opened a dispute to which they replied to within about 20 minutes (Coincedence or not?)