server requires reboot after changing env var?

Hello,

Throughout testing various scenarios with a particular web product and IIS,
I have found the following to be true. Whenever the system path is updated,
IIS will not recognize the change until the server is rebooted. The web
product requires that IIS be aware of the new path in order to find specific
dlls, etc.

** I have been unable to find actual Microsoft documentation or a KB article
to support this claim. Is anyone aware of any such docs? All that I have
been able to find is web sites for third-party people/companies to support
the claim.

Thanks,
Monica.