I have received the famous white screen of death before on modx but this is new to me; it is similar to the WSoD but a 0 is written to the page. The manager page used to work and I have not made any changes to the code on the site in quite some time (although someone has modified page content within modx)...
I am using:
PHP Version 5.2.17 MySql Client 5.0.51a PHP safemode is off.
Any ideas would be appreciated. Could this possibly be something with server memory?
You have of course dumped the cache, deleted all the files/folders in the core/cache directory etc-etc-etc.
Very odd things can happen in the manager if your php post_max_size is too small, not enough memory [at least 32M] your safe mode is right, register globals is off? The only way I found that out was I was tweaking the php settings and forgot the 'M' after 128, leaving my post size at 128bytes ... not good.
Also - I have solved some unsolvable manager problems by moving the manager folder to a backup [mv manager manager.bak] then "upgrading" to the same version.