Hi,
Yes, These are really complecated issues to handle. Normally Wireless Keyboard + Mouse doesn't work in all computers. (Win 98 / 95, or the Buyer hasn't installed the drivers properly).
A perfect transaction will become only when both the seller and buyer has trust. Buyer patience is also a must and should not report to eBay if the seller is prompt is helping the buyer one way or the another.
Telling to eBay about this problem is no use.
The best option is, check your item in different platforms like Win 98 or a older systems. If its working, then convince the buyer to upgrade his system or configure them with the help of some computer hardware engineer.
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With Regards,
Navaneeth (snrama)
😉
---------------
With Regards,
Navaneeth (snrama)
😉