1)HelloUno has a paypal option on the shopping cart page, HelloSleek does not.
2)Using the shopping cart icon, or single-page checkout on HelloUno for Paypal Express checkout, everything works as expected.
3)Paypal checkout works on HelloSleek up until the customer returns to our site (index.php/paypal/express/review/), with HelloSleek the cusomter sees a blank white page, they cannot confirm the order and no charges are made to their account, or orders made in magento.
Both stores use the exact same settings (where permissible, obviously they cannot have the same URLs, etc), however HelloUno works and HelloSleek does not, so this is a theme issue and not a settings issue. Again, this is on Magento 1.4.1