Installing and upgrading help

I am facing a strange behaviore.

If I am using IE to connect to my moodle site, the request mostly times out.
I can see it goes to the index page and tries to load from there other pieces.

Thats where it is getting stuck.

Reloading doesnt help ...
I can see the php process hanging on the machine before it will be killed automatically.

If I am using Firefox the page first time it will get stuck, after reload it seems to work fine.
Until I have to send some post data .. like creating a curse or backup.

Same as with IE now.

Already tried:
I turned off my firewall, allowed all cookies, reinstalled moodle from scratch many times ....

The funny thing: I installed exactly the same setup on my home pc : Suse 9 .. Apache 2
and it ran fine .. the same results (running fine)  with windows &Apache2

moddle data dir is fine: sessions are written correctly and been deleted as well by cron job.

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Since I am hosting at this site many other things like ez lite, mambo, coppermine ...
& all are running without any issue I am a kind of puzzeling what I have done wrong.

Anybody observing similar issues or can spot me to a place where to look for ?
Any help is appreciated.

Thanks !

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my configuration :

base:
moodle 3.3.4
Suse Linux 9.0 , Apache 2 prefork, PHP 4.3.8, mySql 4.0.15

PHP.ini
no safemode
maxMemoryLimit 16 MB
no persitant db links

misc.
checked config.php for strange/not visible characters as suggested.