Yep. If you are talking about IIS, the install will create an IUSER account for this purpose. But it's a lot less secure under NT4 then later versions because the default permissions everywhere else are a bit more lax.
You should run these servers under a limited local user account (or a domain account with similar rights). Then assign the minumum set of file/directory permissions for the services to actually work. No idea about the crash, but have you tried the latest version of PHP?