Cannot checkout after switching host

[Alik]

Switched host and now :

after placing an item in shopping cart - cannot proceed to checkout

also paypal express stopped working when clicking on paypal checkout paypal page loads you log in, click "review Payment" then i a blank page on https://mysite/ipn_main_handler.php?...ayerID=#######


google checkout works fine!



ZC1.3.7
the website is here

[Ajeh]

What happens if you turn off the rewrites?

[Alik]

Cache reset, URL rewrite off....same problem

(Google Checkout still works)