FileReference Issues

I’m trying to use flash to upload an image or mp3. I got it working but I keep getting I/O errors. The first file I tried was 119 KB which worked. The next file was 148 KB which causes the I/O error function to be triggered. So somewhere between those sizes is the cut-off. I’m on an Apache server, and in the SWF’s directory I have an .htaccess file containing:

# These stop HTTP errors 403 & 406
SecFilterEngine Off
SecFilterScanPOST Off
# Increase max upload size and timeout
php_value upload_max_filesize "20M"
php_value post_max_size "20M"
php_value max_execution_time 900
php_value max_input_time 1800
Any help or thoughts are welcome, what do you think?