These two files are missing a slash in a require which is causing an error in the paypal module.

includes/init_includes/init_ipn_postcfg.php

Code:
require(zen_get_file_directory(DIR_FS_CATALOG . DIR_WS_LANGUAGES . $_SESSION['language'] . '/', 'checkout_process.php', 'false'));
includes/modules/payment/paypalwpp.php (line 2199)

Code:
          require(zen_get_file_directory(DIR_FS_CATALOG . DIR_WS_LANGUAGES . $_SESSION['language'] . '/', 'create_account.php', 'false'));
Error Messages

--> PHP Warning: require(/INSTALLDIR/includes/languages/englishcreate_account.php): failed to open stream: No such file or directory in /INSTALLDIR/includes/modules/payment/paypalwpp.php on line 2199.

--> PHP Warning: require(/INSTALLDIR/includes/languages/englishcheckout_process.php): failed to open stream: No such file or directory in /INSTALLDIR/includes/init_includes/init_ipn_postcfg.php on line 22.