SWFUpload Upload Error: 500 Problem

Recently i got a client who wanted me to build a custom multiple upload function with SWFUpload into Amazon S3. There is a small introduction in case you have no idea what is SWFUpload or you want to build one up yourself, you can visit Tutorial: Cross browser Multiple Uploader With SWFUpload And JavaScript. After testing etc. everything went smoothly on my side until the program is being integrated into his server. Upload Error: 500 was appearing and causes the upload to fail.

The Problem

The problem is with flash 10 that seems to be incompatible with mod_security. This caused the flash player to fail which result in an Upload Error: 500 on SWFUpload. The other thing that also might caused it to display Upload Error: 500 was the file limit set on the server.