AJAX mass processing provokes errors

Hello
My company wants to create a recurring report, that ignores all values that already are in a report.
(background: they create monthly invoices for their customers, which are based on the order_product status instead of the order status)
So i created a javascript function that creates a ajax request for each order_product that is displayed in a list.
But when the amount of ajax requests gets very high (>500), some of the requests get errors returned.

could it be that the amount of requests is too high for my server?


VQMOD: Could not delete vqmod/vqmod.log. Verify path has read/write accessWarning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/xxx/domains/xxx/public_html/vqmod/vqmod.php:224) in /home/xxx/domains/xxx/public_html/system/library/session.php on line 11{"success":"goed zo!"}


Fatal error: Class 'Loader' not found in /home/xxx/domains/xxx/public_html/admin/index.php on line 29

VQMOD: Could not delete vqmod/vqmod.log. Verify path has read/write accessWarning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/xxx/domains/xxx/public_html/vqmod/vqmod.php:224) in /home/xxx/domains/xxx/public_html/system/library/session.php on line 11{"success":"goed zo!"}
error setting 4773

Fatal error: Class 'Front' not found in /home/xxx/domains/xxx/public_html/admin/index.php on line 133
error setting 5735
VQMOD: Could not delete vqmod/vqmod.log. Verify path has read/write accessWarning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/xxx/domains/xxx/public_html/vqmod/vqmod.php:224) in /home/xxx/domains/xxx/public_html/system/library/session.php on line 11{"success":"goed zo!"}

VQMOD: Could not delete vqmod/vqmod.log. Verify path has read/write accessWarning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/xxx/domains/xxx/public_html/vqmod/vqmod.php:224) in /home/xxx/domains/xxx/public_html/system/library/session.php on line 11{"success":"goed zo!"}


Fatal error: Class 'Loader' not found in /home/xxx/domains/xxx/public_html/admin/index.php on line 29