The way Apache is restarted and the WO adaptor

Happy New Year to All.

I was wondering if any of you has ever observed an Apache server suddenly
not loading the WO module as expected.
Here is my environment:

WO 5.2.1
JDK 1.3.08
Apache 1.3.27
SUN/Solaris 5.8

We have restarted Apache every night via a graceful restart for ages, but
now, for some reason that I can't explain, sometimes we need a manual
stop/start to force the WO module load.

In fact, applications that were running fine the day before are not
responding in the morning. To be more precise, calls to URLs such as
"http://myHost/module/WebObjects/MyApp.woa" result in errors like the
following:

[Tue Jan 09 08:57:30 2004] [error] [client 124.735.13.143] File does not
exist: /usr/local/apache/htdocs/module/WebObjects/MyApp.woa

as if Apache had been looking for a static page under
/usr/local/apache/htdocs/module/ (a directory that does not exists) instead
of routing the request to the WO adaptor as expected. All goes back to
normal when we manually stop and start Apache again.

Does this mean that a "graceful" shutdown isn't equivalent to a stop/start
as far as loading the WO module is concerned?
And why this change, as nothing has changed in our environment for months?

If you have any idea, don't hesitate...

Thanks in advance,
ciao
laura