yes, sorry. You need to rename the files checkout.xml, paypal.xml and paypaluk.xml to __checkout.xml, __paypal.xml and __paypaluk.xml on app/design/frontend/default/hellosleek/layout. And folders checkout, paypal and paypaluk to __checkout, __paypal and __paypaluk on pp/design/frontend/default/hellosleek/template.
The cause is because when not find the checkout.xml (eg) on the theme, take automatically the file on base theme. Base theme is always update, because when Magento upgrade the core, this folder change too.
Hope it helps.