[imp] email page with 'loading' for ever on Horde webmail 5.0.2

[Eric Van Bocxlaer]

Hi,

Running Horde Webmail now for years from 3.x to 4.x without any 
problem.
Running it on : Windows server 2003 with Apache/2.4.3 (Win32), 
PHP/5.4.4, MySQL5.5 and imap server hmailserver5.3.3

Sunday I did the update to horde 5.0.2 using PEAR. The upgrade went 
wel.
I could login to the new dynamic view and could do the configuration 
changes(updating database and config).
I can see the agenda, the addressbook and the notes, but the email page 
gives a 'loading' for ever.
I had 2 or 3 times that the left tree with the folders was loaded after 
some refreshes. In that case I could click on a map and the emails are
loaded, but I couldn't open the emails.
Sending an email works. (I have a backup-email system Roundcube, 
installed on the same server, with the same apache and php version and 
there I see my emails)

So what did I already as tests:
- with fiddler I see that the two ajax calls ViewPort and ListMailboxes 
are returning an error 504 (session was aborted)
- in the apache error log I see at the same time: [mpm_winnt:notice] 
[pid 7316:tid 532] AH00428: Parent: child process exited with status 128 
-- Restarting. (the error number is not really helpfull)
- In the horde logfile there where some errors: ** HORDE [imp] PHP 
ERROR: Use of undefined constant D_FMT - assumed 'D_FMT' [pid 548 on
line 42 of "C:\php\pear\Horde\Core\Script\Package\Datejs.php"]
    --> corrected that in the source code, the error went away but the 
main problem, no email, is still there
- In the hmailserver logfile I see the connection for the retrieving of 
the mailboxes and the emails, with a correct "SENT: 5 OK UID completed"
- the Horde test file is given me the same results as for the previous 
versions, all green except for some pecl extensions not running on 
windows system
- I increased the memory_limit in the php.ini file from 128M to 512M 
but no change

So something is going wrong when creating the JSON response for the 
ajax calls.
I changed in the configuration file the log option to see the DEBUG 
information. But, for what I can see, that is not giving more 
information.

Today I did a complete deinstallation of horde via PEAR and a reinstall 
via PEAR, but same result.

On this server I don't have a ZendStudio or something equivalent to 
debug.
I added some print_f for manual debug, but not knowing the source code 
workflow, that's difficult. (+ it is several years ago that I programmed 
in php ;-) )

Can somebody tell me where to start to debug this problem? It worked 
with the previous versions of horde, so it must work with the current 
version!


Regards,
Eric