We live in an area where many planes pass overhead, although we are
about 20 miles from the airport.  Our home computer freezes up
momentarily whenever a plane passes over. You will be typing and
nothing happens for 5-10 seconds before you can continue. This seems
to happen especially on rainy or foggy days.  It is incredibly
annoying.  It happens whether or not we are connected to the internet.
 We have had the computer checked out and it is completely fine.  We
have complained to the airport and received acknowledgement of the
problem but no answers.  People have suggested putting the CPU on a
pad in case it is due to vibration, but that makes no difference.  I
want to know if this is a common problem and what we can do about it. 
Thanks.

Weird! Are you using cordless mouse or keyboard? Wi-Fi etc?

regular keyboard and mouse

Are the covers on your system?
Is your system plugged into a UPS?  Might help?
If nothing else try wearing a piece of tin foil on your head.  It
won't help but the rest of the household will get a chuckle!  Good
luck

sounds like it could have something to do with static electricity

This is extraordinarily peculiar. Discounting alien intervention etc,
and you say none of your attached devices are radio linked, when you
are off-line do you disconnect the lead from the socket?

The only thing which could possibly get into your machine is RF. Where
and why though. It might be radar or comms (either to or from the
plane), of automatic ID signature from the plane (can?t remember what
it?s called). Strange that it is so consistent and repeatable. It?s
not likely to be the frequency itself which is interfering with your
machine -- it just shouldn?t get in. More likely it?s one of your
leads resonating, perhaps generating a DC offset due to non-linearity
or incidental rectification. More likely it?s hanging up the keyboard
and not your computer. Try a different one.

You may be familiar with the principle of ferrite suppression. Often
there?s lump on a peripheral lead -- this is a ferrite sleeve. What
should happen is that ferrite absorbs (potentially) interference
radiation and to a lesser extent prevent incidental radiation from
entering. Unfortunately, the principal of absorption is not always
recognised by designers and they incorporate inappropriate ferrites.
Instead of absorbing energy, these ferrites largely reflect it. It
stops the radiation going anywhere OK but you can end up with an
extraneous signal blatting back and forth along a wire, building up in
amplitude until something gives. This *is* an unlikely scenario but so
is your problem! I wonder if there is a local high power airport
transmitter repeater which you don?t know about.

What you can try, aside from the keyboard, is scrunch up your leads to
less like aerials, swap the mouse, or even experiment with clip-on
ferrite suppressers. Unplug anything not essential, try running only
on UPS (no mains lead). Essentially just home down on where the junk
is coming in. If it is the keyboard screwing up, it?s not necessarily
the keyboard which is to blame, just that it is the bit that gets
?hit?. As you may know, a keyboard ain?t just a dumb bunch of switches
but has it?s own processor.

Let me (us) know how you get on. I?m intrigued.

Best

Thanks very much for your interest & helpful suggestions!  I will try
switching keyboard, mouse, etc.  What you said about "local airport"
might be something---there IS a small airport a few miles away, which
I forgot about (the major aiport is 20+ miles).  Will try to look into
that.  Your expertise appreciated.  If there are any changes, I'll
update here.

Just occurred -- is it when a plane is on approach or take off path?
Foggy and damp makes me wonder about bad weather guidance systems.

Looking forward to answer :-)

What about your neighbors? Do you know if there is another person in
the neighborhood who has the same problem?

dwald-ga:

guzzi-ga is on the right track, I believe.  

Here are some reasonable guesses: It is very peculiar and sometimes RF
problems ARE like that.  First time I read the question, several other
questions came to mind.  One of the possibilities is that you have a
VOR/DME station nearby and when the airplanes transmit pulses to the
DME (distance measuring equipment), the DME replies (using fairly high
power, compared to airplane power output from it's interragator,
talking to the DME station (and the airplane is probably further away
also)).  So if the station is close to you, it may cause interference
- especially if your computer clock frequency is in the 1.0 to 1.2GHz
range.

[There are also some L-Band primary surveillance radars that operate
with high power, approximately in the 1.2-1.3GHz band, but since they
should be operatign all the time, airplane going overhead shouldn't
matter (the reflected power from each airplane is very small).  There
are other airplane based emitters, but those are generally outside the
frequency range and lower power.  Generally I'll suspect ground
stations because they operate in higher power than airplane emitters
and are likely closer to you].

Make sure the computer case is closed properly (all screws in place)
and the power/mouse/keyboard cables are as short as possible.  If your
computer is running at the clock frequency of 1-1.2GHz, try to slow
down the computer clock to 900MHz or speed it to over 1.2GHz (search
for "overclocking CPU" on google, your BIOS may support it) and see if
the problem persists.  You can also experiment wrapping the cables
(most of the length) in aluminum foil and grounding the foil to the
computer case.

If none of that works, consider telling us your location (or airports
and distance(s) from them & direction), CPU clock frequency, whether
you are using extension cables (power, mouse, keyboard, USB, ...),
whether the airplane is directly overhead or at approximately the same
azimuth & altitude ("location") relative to your house and how you
came up with the correlation.

--
I am not an official GA researcher.

Can't help with why it does, but I can comment on it not being common.
We are just next to the flight path for a local RAF/USAF base and get
allsorts of Miltary aircraft, F15,C5s,C47,C130 etc etc flying past. (I
can usually read their registration numbers so they are very low). We
have several PCs in the house, using WiFI, wireless mice etc and I'm
also very prone to leaving the cases off etc.

We've had no problems at all.

Does the who'll computer freeze or just the keyboard and/or mouse i.e
does the PC clock tick over/video/music etc carry on.

Ta athena4 for filling in authoritative transponder details -- and I
was going to suggest the clock details but icehouse thinks faster than
me :-) But as he (she?) said, when it freezes, does your clock lose 20
seconds too.

I?m inclined to suspect that the lock-up isn?t at the processor native
frequency because one might expect blue screen or one of Microsoft?s
inscrutable error messages, but maybe.....

1st - if you think that is static/electric noise that interfere with
your computer try rap it in kitchen silver paper and connect it to the
house ground or some big metal part like the pipes in your house...
2nd - maybe you should use an electical stabilizer insted of ups if
the problem is caused by the electricity company.

try this and goodluck

I am both a pilot and a computer technician.  I believe the thread is
on the right track regarding the VOR/DME station nearby and the planes
own instrumentation.  Have you considered building a Faraday Cage
around your computer?  Most commonly, they are used to protect against
lightning, however they do a fantastic job of protecting against all
sorts of waves.  I have had to use a similar device with a computer
residing near LAX.  In that case the monitor would distort whenever a
plane would pass directly overhead.  Here is a couple of links to
describe what this is:

http://en.wikipedia.org/wiki/Faraday_cage
http://www.boltlightningprotection.com/Elemental_Faraday_Cage.htm