I don't think that NAV is your problem. In IIS 4.0, ASP can hang there for a while and crash very often. It's been a problem for long that no one can really solve.

If you call up MS, they'll try to get everything that is not MS out of there. Like they say, if you can blame it on someone else then there is no problem...

May I suggest that you migrate to Win2k with IIS5.0. The ASP hanging thing seems to have been solve in IIS 5..