Why won't some Avatar's Upload?

Some users have been having problems with the Avatar Upload in profile. When I tested it it works. Users report the error message as

Error uploading image
The image uploaded is the wrong file type.
Images must be of type, gif, jpg, jpeg

So I asked a user to email me the image she was trying to upload. She sent me a jpeg file - loads fine in any application on my Windows XP computer. Size at 79 kb was a bit large but maximum Avatar file size was set to 200 Kb. Yet I got the same error when I tried to upload it.

I opened it in Paint, changed its size a bit and resaved it, still would not accept it. I changed the size to something much smaller and it worked.  So I then tried different sizes to see if I could find a limit and all worked, including one much larger (more pixels) than the original.

So what is going on? Why do some versions of this image saved by Paint work, while others don't ?

I'm using v 9.06 hosted by WebWiz, with Persits AspUpload, 10 Mb upload space per user, 200 kb max Avatar size.

Thank you Bruce, I know that at least one of the users having problems created the image in Adobe Paintshop on a Mac, so that sounds like the cause of the problem.

I thought our hosyting package included automatic free upgrades? How do I tell which version we are running?

Many people who host their Web Wiz Forums with us don't like to have their forum automatically updated for one reason or another.

If you would like your Web Wiz Forums installation updated then please contact Hosting Support through your Client Area account and we will have your forum updated for you. We will also be able to tell which version you are running. If there is anything that you have modified then please also let us know.

Version 9.50 has a new 'Check for Updates' tool in the admin area, when this tool is used it will tell you what version you are using and will also connect to our own update notification server to tell you the latest stable release available, so you can easily check that you are up-to-date with the latest release.

I doubt if they would do this, as any modifications people may make they do at their own risk. Whilst this is a helpful web host, it could literally take ages to implement any updates or mods we or others had made

Personally I believe its more beneficial to do the changes or mods again, as that way you learn and can pass on your experience to others. Obviously though that's only my own opinion