Too stupid to realize one's stupidity

It always tickles me when a customer is too stupid to know that the problem is because of their stupidity and not because of a genuine problem. Its totally fine if you don't understand something, there are plenty of things I don't know either, but when there is a problem because a person doesn't understand how to do something and they try to blame me for it, then I have a serious problem with it. Take for example this eMail from today:

"The unit sent to me (Item number: ********) will not load an OS. Its a BSD everytime.Please rectify, negative reviews really aren't my thing. Please contact me 212-***-**** Thanks
- c*tex****"

Now obviously this idiot doesn't understand how to load his XP drivers correctly when doing an install and his workstation is giving him exactly the screen at exactly the time it is supposed to....prompting him to follow the proceedure that the workstation is expecting him to. That he does not know that is not what makes him an idiot.

What makes him an idiot is the fact that he assumes his ignorance is my fault and that he has to be threatening (as in "negative reviews aren't my thing" Neither apparently is common sense.)

Use your head people! Enough said