Hi there,
Are you using the main PayPal email? This is required because when using paypal ipn, if you use secondary paypal email associated to your account, paypal will report the main one and quicksell will drop the order as fraud attempt.
The mail you are getting, is it the one with subject "verified order on ...."?
I would love to help you out resolve it asap. It works great on many websites, I'm pretty sure ordering system is pretty stable, but who knows!
I'm also on skype bbh2k3.
Thanks!