Internal error when trying to checkout

Hi all,



I get following message whenever customers try to click cart or checkout button:


[quote]

Internal Server Error

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

Please contact the server administrator, 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 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

[/quote]



I also talked to host and they told me that the problem is with the script and he emailed me the log info:


[quote]



[Tue Feb 12 09:46:39 2013] [error] [client xxxx] Premature end of script headers: index.php

[Tue Feb 12 09:46:39 2013] [error] [client xxxx] Premature end of script headers: index.php

[/quote]



I have opened ticket also, but if someone knows how to solve this, I would appreciated.



Thanks,

Urko do you solve the problem? and how?



Thanks