I have a Canon SD300 digital camera which captures video as well. 
Canon says that the camera video shot in standard mode will run on a
computer using Apple's Quicktime (or Windows Media Player) as long as
it meets certain requirements.

My system has more than 3x the system requirements specified by Canon.
 Also, I have played many videos on my computer before--even videos
from another Canon camera.  However, the SD 300 videos just stop,
start and jump around and don't show properly.

I have tried this on three different computer systems owned by
different people yet we all have the same result.  I called Canon tech
support and their tech support people said they recreated the same
problem on their end but they could not fix it.

Why won't the videos run, and what can I do to fix it?

Please don't tell me that my system memory is back up (it's not) or
that my computer processor isn't enough (Pentium 4 1.7 hrtz with 500
MB RAM).  I've check for all that stuff.

i can say that the video runs fine on the camera; just not on the
computer.  Again, however, videos from other cameras of the same
megapixel run fine on my computer.

From what little I know about the SD300, you have several options when
selecting which "video mode" to shoot in:

 - Standard: 640 x 480/320 x 240 pixels
 - Fast Frame Rate: 320 x 240 pixels
 - Compact: 160 x 120 pixels

  The first thing I would try is to change that mode on the camera
between attempts, and see if any one mode plays better on the PC.
(Yes, they should all work, but if none of them work, then we rule
that out.)

Assuming that does not work, the next thing I would check is to ensure
that there is no specific video software that Canon shipped with the
camera that might work better in playing the files.

Finally, and on a related note, I would check to ensure you have the
proper codec installed on your PC to play the files correctly. (Your
PC certainly sound s like the hardware is sufficient, but certain
drivers or codecs may also need to be installed to get it up to date.)
 The movies are saved in AVI format, using the M-JPEG codec.  You can
Google for info about the M-JPEG codec, and download and install it
just to be sure. (I like the K-Lite codec pack, but I am not sure
whether it includes the M-JPEG codec .)

Hope that helps...

Hey Douglas, I'm going to do my best in attempting to help you with your problem.

According to your description, the first thing that comes to mind is
video corruption. If the movies are in-fact skipping around - the
video files themselves could be corrupted. When transferring your
files from camera to computer, ensure that your camera is not located
anywhere near a magnet (Such as a speaker magnet, ect) as this can
cause corruption. This seems like a very simple thing, and more than
likely isn't your problem - but still something to consider.

It was previously mentioned that your camera saves video in .avi
format with the M-JPEG (Motion JPEG) codec. The decompresser for this
codec is installed by default within most computers today, and more
than likely is not the problem. The fact that the video PLAYS (Albeit,
messed up) shows that you do in fact have a decompressor for the
codec's compression format.

You can also run a test on these video files to see if they are indeed
corrupted using a diagnostic program called G-spot. G-spot will
analyze any video and inform you if there are any problems, IE. if the
headers of the video are corrupted. It will also tell you what codecs
are required to play the video, and if you do have the compatible
codecs installed on your system.

You may want to try playing your movies within multiple media players,
such as QuickTime, Winamp, or BSplayer. Occasionally a movie will work
within one player, but not another. You can download these
applications at the following URLs:

http://www.quicktime.com
http://www.winamp.com
http://www.bsplayer.org

Lastly, you may want to check if your video card is running in full
hardware acceleration mode. You can do this by going to your display
properties (Control Panel), and then clicking on advanced, and then on
the "Troubleshoot" tab. Make sure this slider is set all the way to
the right.

If none of these attempts work, I would be inclined to believe that
your problem lies in a hardware defect, or the movies themselves are
corrupted (Or both). The fact that Canon could replicate the same
conditions & problems that you had, leads me to believe that this
could very well be a hardware defect.

Either way, I hope this response has helped you!

Best Regards,
Joseph.

Ahh! I forgot to give the link for G-Spot. You can download this tool
here: http://www.headbands.com/gspot/

Best Regards,
Joseph.

If you looking for more information on the Canon SD300 you might also want to try
here.

http://www.bargainfindsonebay.com/canon/Canon_PowerShotSD300.html