Photos may not exceed a maximum filesize of 460800 bytes or may be no more than 1200 x 1000 pixels in image size.
I could not locate any error logs in the photo gallery for your username. Chances are your session is timing out due to a very slow dialup connection possibly in combination with an oversize picture file. Try cutting your photo down to about 640 x 480 pixels (which will cut the file size down and probably speed up the upload time) and see if that works for you. Also check to make sure that you are in fact trying to upload a supported photo format (jpg, jpeg, gif, or png). If the problem is not a case of unrecognized file formats, oversized images and/or maxed out file sizes then contact the pethobbyist photo gallery coordinator for additional assistance.
Pet Hobbyist.com Contact Page (under department scroll through the list and select the photo gallery coordinator name)
Something else to keep in mind is that this time of year, a lot of people are getting new computers so that internet usage is much higher than normal and that tends to really bog down the internet's speed in general. This really makes headaches for everyone (especially in the evening/night hours) so it's possible that your photos may actually be fine size & format wise, but it's just the internet itself that's the problem. In years past I've noticed these kinds of slow downs tend to taper off after a couple of weeks, usually by the end of January. Trying to upload files in the morning or early afternoon hours may help offset some of that, but no guarantee.
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PHWyvern