To whoever answers this:
 Please be patient and read the whole question - there is a lot of
detail.
Background:
 Independent computer consultant.  Over the last three years I've
grown a substantial business going to people's homes and fixing their
computers.  I generate a lot of business via advertising, and a lot
through word of mouth.
 One woman answers my ad.  She just got divorced and needed some help
with her PCs.  She calls me periodically, always seems happy with my
work.
 She moved into a different home and got Optonline cable.  She asked
me to network everything with a wireless router.  I bought a router
and an adapter, and set everything up.  However, on one machine the
wireless acted flaky, so she told me she'd think about perhaps putting
it on her son's machine instead.  But she had to go on a vacation, and
would re-connect when she came back.
 Keep in mind that she has always been friendly, nice, and always paid
me exactly what I asked for (some customers try to get me to lower the
bill).
 Also keep in mind that I took the equipment out of the boxes, and
kept the boxes - for no other reason than to cut down on the already
massive clutter in her new home.
 So everything seemed OK, and I figured she would call me when she got
back.
 She did, but the call wasn't what I expected - she called me out of
the blue from her cell phone (on my cell phone), sounding upset,
asking why she didn't get any boxes.  I told her why, then she started
arguing about it.  I simply listened to what she had to say, but the
call was breaking up badly.  She asked me if I thought she could
switch the network adapter from one PC to another, and I told her she
should be able to.
 She writes back to me a couple of days later to let me know that it
didn't work, becaus she thought she had the software (I thought I had
left it, but didn't).
 I left her a phone message at home offering to burn some updated
driver software on CD and that I would be happy to set the adapter up
on the second machine at no charge.
 Her email reply was very curt - "just give me the software and boxes
I paid for and I'll do it myself."
 I checked and found that I had thrown the boxes away.  So in the
spirit of doing the right thing, I bought both products again, removed
the products (I can always use them in my business), and dropped the
boxes (with software) with her housekeeper.
 I'm still not sure why this woman seems to not trust me anymore, or
perhaps even doesn't like me anymore.
 My business has succeeded because of my promptness, likeablility, and
honesty.
 What I'd like do is send her an email (she clearly prefers to
communicate this way), and simply ask her what it is I've done that's
bothering her.
 Should I bother asking? If so, how should I best go about it?

 Thanks...

pcventures-ga,

After reading your account of the situation, I must say that thus far
you have acted in a completely professional manner. A slight exception
to this was your not leaving her the product boxes in the first place
(when a client buys PC/network equipment through you--they own it and
deserve to get everything that came with it, including the product
boxes, software, manuals and registration cards, unless they tell you
specifically that they’d like you to take the boxes away for them).
However, since you promptly returned the boxes and (which you had to
buy again, new)and software to her, you corrected this slight error in
a professional manner.

At this point, since your client has informed you that she considers
this particular job to be complete (“just give me the software and
boxes
I paid for and I'll do it myself."), and you effectively returned the
boxes to her, there is nothing to do but consider this job completed,
and move on.
Since your client seemed upset by the matter, and she’s a repeat
customer, however, I think it would be worth your time to write her an
apologetic e-mail explaining that

1)You value your relationship with her as a customer 
2)You’re sorry for forgetting to leave the boxes and it won’t happen
again
3)You just wanted to follow up on the job itself to make sure her
system is now working properly.

This is a very simple and easy step for you to take, so you might as
well do it. I do not think that you should ask her in the letter “what
is bothering her,” as it implies that her behavior is perhaps at
fault, and the customer must always be right (especially for small
business owners such as yourself).

Also, you did not mention if she has already paid you for this job or
not. If not, I assume that you bill the client at the end of each job,
and so if I were you, I would bill her at this time if you haven't
done so already. I would keep the billing a completely separate matter
from your apology e-mail, though, and send the bill a couple days
*after* you send the e-mail as desribed above, or perhaps after you
receive her response to your e-mail (if she responds).

I’ll stop short of actually writing the text of the letter for you,
given your Question’s price, but I’m sure that you can handle it from
here.

Good luck with your business!

Sincerely,

omniscientbeing-ga
Google Answers Researcher

Very good - thank you!

It could be that your likeability and friendship has been interpreted
as overfamiliarity and complacency. I recently had my carpets cleaned
by a guy with very good people skills. I know he had them because he
told me -- several times. All I wanted was clean carpets, not a
relationship.

It could be that your mistaken assumption of her not needing/wanting
the product boxes and forgetting to leave the software has offended
her and given her cause not to trust you. Maybe she thinks that you
think she's a dummy and she feels uncomfortable and 'stoopid' around
you. Maybe she's just really, really busy and wanted you to sort out
her connection issues quickly and without incident, which, honey, you
didn't. Sure, a follow up email is fine, but keep it short, light and
fairly impersonal, and let her know you're getting in touch to make
sure she's happy with the service you've provided and to explain the
misunderstanding and to confirm that warranty etc was never
compromised as a result of you taking the boxes. Hopefully this will
give her the opportunity to advise you of any issues she has with your
service.If she doesn't respond, then you'll just have to chalk it up
to experience and move on.

A possibility not yet mentioned: This woman mentioned to a friend,
colleague, or another computer person that she had problems with her
hardware. That person asked her about the products and, upon learning
that you hadn't left the boxes, suggested that you may have given her
used or returned merchandise. This misperception may have been further
exaggerated when you offered to burn her a CD with the software,
rather than providing the original disks.

I am not trying to state that this *is* what happened, but it is a
plausible scenario consistent with her suspicions and reactions.

Hello:

I'd like to offer you an opinion of what 'could have' happened.  Keep
in mind what I am offering you is just speculation, but nevertheless,
possibilities.

1. Maybe she was just in a bad mood that day and decided to take it
out on you. Things not working probably added to the frustration, if
that was the case.

2. I think with the box issue, perhaps she was a little ticked off
that she was not offered the boxes as proof that the parts were
purchased as new.  Maybe in her mind she may have felt you 'could
have' given her something used, but charged her for new parts.  In any
event, I think its a good practice to offer the customer the box ahead
of time and chalk this incident as 'lessons' learned.  Maybe she just
likes to keep boxes "in case she has to move."

In any event, I think if you wish to salvage the relationship, its
best to call her to talk about the incident and work it out.  There's
obviously something bothering her, but the problem is you don't know
what.  I wouldn't let it go.

NEVER try to understand women.

There's a book somewhere that explains everything (Pinkfreud will know
the ISBN) ...

Something about 'Men are from Heaven ......'