We’ve recently encountered an issue where in the Magento Community Edition v1.6.x branch, when compilation is enabled it can cause a blank page (also known as “White Screen of Death – WSOD”), in the cart and checkout sections of the Magento frontend.
It’s not the easiest problem to resolve, as it gives no errors, no logs or possible hints as to what’s causing the problem. But alas, we’ve found the solution/work around!
This is caused by having “Persistent Shopping Cart” enabled in your admin panel, if this is disabled then you won’t encounter this frustrating problem with Magento Compilation enabled.
To change this option, login to your Magento Admin Panel and go to:
System > Configuration > Persistent Shopping Cart > General Options > Enable Persistence (set this to disabled)
Hopefully this issue will be resolved in the Magento v1.7.x branch. Until then you’ll be unable to use compilation and persistent shopping cart together.