http://www.php.net/manual/en/feature...n-pitfalls.php
The MAX_FILE_SIZE item cannot specify a file size greater than the file size that has been set in the upload_max_filesize ini-setting. The default is 2 Megabytes.
If a memory limit is enabled, a larger memory_limit may be needed.
Make sure you set memory_limit large enough.
If max_execution_time is set too small, script execution may be exceeded by the value. Make sure you set max_execution_time large enough.
Note: max_execution_time only affects the execution time of the script itself. Any time spent on activity that happens outside the execution of the script such as system calls using system(), the sleep() function, database queries, time taken by the file upload process, etc. is not included when determining the maximum time that the script has been running.
Warning
max_input_time sets the maximum time, in seconds, the script is allowed to receive input; this includes file uploads. For large or multiple files, or users on slower connections, the default of 60 seconds may be exceeded.
If post_max_size is set too small, large files cannot be uploaded. Make sure you set post_max_size large enough.