Description:
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On a production site using PHP5 5.0.3 with Apache 1.3.33 we see random session_start hangs. It does NOT happen always on the same page, with the same client, the same frequency or unter the same load.
If it happens the process eats up all CPU time util it reaches the 'max_execution_time'. It then leaves a trace in the error log saying:
PHP Fatal error:  Maximum execution time of 15 seconds exceeded in XXX on line XXX. There are always other pages and lines.
I already tried a lot of stuff to see if there is any influence like using 'session_destroy'. I do not use any special session parameters. The actual parameters are:

[Session]
session.save_handler = files
session.save_path = /home/teviaqui/session
session.use_cookies = 1
session.name = PHPSESSID
session.auto_start = 0
session.cookie_lifetime = 0
session.cookie_path = /
session.cookie_domain =
session.serialize_handler = php
session.gc_probability = 1
session.gc_divisor     = 1000
session.gc_maxlifetime = 1440
session.bug_compat_42 = 0
session.bug_compat_warn = 1
session.referer_check =
session.entropy_length = 0
session.entropy_file =
;session.entropy_length = 16
;session.entropy_file = /dev/urandom
session.cache_limiter = nocache
session.cache_expire = 180
session.use_trans_sid = 0

I am also a developer and might help to debug the code but I need some advice where to lock at!

Reproduce code:
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session_start ();

Expected result:
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I would like to see no processes eating up all the CPU time of our sever.

Actual result:
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The the moment I have several httpd processes hanging at the same time eating up all CPU time. There are about 120 users browsing the site.
At the moment it happens like 30 times every hour!