Here's a strange one for you ...
Have a normal 32bit AMD Athlon PC and an AMD 64 PC.
The 32bit PC is running Debian Sarge 2.4.27-2-386 and MySQL 4.0.24
The 64bit PC is running Debian Sarge 2.6.12-1-amd64-generic and MySQL 4.0.24
A working Drupal site on the 32bit PC, when migrated to the 64bit PC exhibits the following two strangenesses:
(1) All pictures stop working - and yes, the picture are all there and can be retrieved separately by the browser but do not show up in the pages (I have the picture handling method set to private). It's only uploaded pictures that are the problem, not site logo, etc. Is the issue the fact that the site is a migrated one and nothing to do with the 64bit Debian?
(2) A PHP memory limit of 24M was fine on the 386 PC but had to be increased to 32M on the 64bit PC. Otherwise, big blank page time.
Any ideas???