"ipn_main_handler.php?type=ec" resulting in blank page

I can process an order through to paypal with free-shipping, and I was able to process using australia post shipping module, however as soon as I enable more than one shipping module, ipn_main_handler.php?type=ec results in a blank page. also many of the other shipping modules indipendantly result in a blank page, per item for instance. something very odd and very frustrating. any ideas? site is here: http://duoplecguitarpicks.com.au/shop/
I have managed to set up a few other zencart sites on the same server without hassle, anyone??? thanks in advance.

Searching the FAQs for "blank page" brings up this article: https://www.zen-cart.com/tutorials/index.php?article=82

here is my paypal log file, for a sale that went through to a blank page.:

2011-08-31 12:13:13

(live transaction) --> https://api-3t.paypal.com/nvp
Request Headers:
Array
(
[0] => Content-Type: text/namevalue
[1] => X-VPS-Timeout: 45
[2] => X-VPS-VIT-Client-Type: PHP/cURL
[3] => X-VPS-VIT-Integration-Product: PHP::Zen Cart(tm) - PayPal/NVP
[4] => X-VPS-VIT-Integration-Version: 1.3.9h
)

Request Parameters: {SetExpressCheckout}
Array
(
[AMT] => 0.50
[ITEMAMT] => 0.50
[L_NUMBER0] =>
[L_NAME0] => test product
[L_AMT0] => 0.50
[L_QTY0] => 1
[LOCALECODE] => AU
[PAYMENTACTION] => Sale
[ALLOWNOTE] => 1
[LANDINGPAGE] => Billing
[RETURNURL] => ***** REMOVED *** *
[CANCELURL] => ***** REMOVED *** *
[PAGESTYLE] => Primary
[METHOD] => SetExpressCheckout
[CURRENCYCODE] => AUD
[USER] => *************
[PWD] => ****************
[VERSION] => 60.0
[SIGNATURE] => ****************************************************4ebM
)

Response:
Array
(
[TOKEN] => EC-2BA79042M3906915M
[TIMESTAMP] => 2011-08-31T02:13:13Z
[CORRELATIONID] => 3921a204e28bf
[ACK] => Success
[VERSION] => 60.0
[BUILD] => 2085867
[CURL_ERRORS] =>
)

SetExpressCheckout, Elapsed: 1550ms -- Success

thanks DrByte - i'll try that and report back.

That log only confirms that the first step of asking PayPal for a token for the transaction worked properly.

ohhh. days of frustration. finally success. :clap:
I ftp deleted and re-uploaded just the paypal modules with no success.

then I ftp deleted and re-uploaded.

• includes/modules
• includes/languages/english.php
• includes/languages/modules
  and it now works.
  thanks.
  I hope this helps anyone else with the same problem.

Sounds about right.
As indicated in the FAQ article I pointed to, the most common cause of blank pages is improperly-uploaded files.