Emergency: 500 Internal Server Error

Hello.

(I dont know if this is the correct place for this, else, please says to mi what is the correct place)

I was editin the control access for a node web form, and after
i submit Durpal start to showme this...

(Is only show on super administers users, whit others user the page run fine)

Where start to fix this?

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@siiee.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
Apache Server at www.siiee.com Port 80

This is the log from the server error log

[Mon Dec 19 18:54:17 2011] [error] [client 190.71.32.150] ] [notice] EACCELERATOR(30985): PHP crashed on opline 63 of format() at /home/siieecom/public_html/Proyectos/HappyBox/sites/all/modules/webform/webform.module:3490

[Mon Dec 19 18:54:04 2011] [error] [client 190.71.32.150] File does not exist: /home/siieecom/public_html/500.shtml, referer: http://www.siiee.com/Proyectos/HappyBox/admin/structure/block

[Mon Dec 19 18:54:04 2011] [error] [client 190.71.32.150] ] [notice] EACCELERATOR(30754): PHP crashed on opline 63 of format() at /home/siieecom/public_html/Proyectos/HappyBox/sites/all/modules/webform/webform.module:3490, referer: http://www.siiee.com/Proyectos/HappyBox/admin/structure/block

I know nothig about servers

PLEASE HELP!