How did the user exceed the per-image file-size limit, and upload much larger files?

We are registered users of Aurigma Image Uploader 4.1.

The Image Uploader seems to be working fine on our site for the most part. However, something happened recently, that has left us feeling puzzled.

1. We have set a file-size limit of 200-KB per image, and the Image Uploader successfully filters/blocks files that are too big, and does not normally allow the user to upload files larger than 200-KB in size.

2. However, we found out recently that a user uploaded files that are about five times the size (up to 910-KB each). We are puzzled as to how that might have happened, and why/how the Image Uploader allowed them to bypass/exceed the per-image file-size limits. When we try to replicate the problem at our end using the same 910-KB file(s) that the user uploaded, the Image Uploader seems to successfully block them, and does not even allow us to select them for "Send/Upload".

My questions now are:

a. Are there any web-browsers out there (or any other known issues/methods/hacks) that will allow a user to circumvent/bypass Image Uploader's file-size filtering mechanism?

b. What technique could the user have used to upload the large files, and how can we prevent this from happening again? In looking at the uploaded files we are reasonably sure that the actual code on the page where Image Uploader is embedded was used (and not direct FTP for uploading the files) because the file renaming scheme is the same that a properly uploaded file would be expected to have.

Any advice/help would be greatly appreciated. We use Windows XP Pro, and IE 7.0 (the code is in ASP .Net). However, the user seems to have been at a University/Educational Institution, and there is no telling what operating system or browser they might have used.

Thank you.

Regards,

Mona.