I'm having an issue w/ DNN 4.2 on a 64 bit server.  I've set up DNN 4.2 on XP Pro, Win2k3 Standard 32 bit and Win2k3 Standard 64 bit.  The only instance that's having an issue is the 64 bit server.  When a user inputs the incorrect user name and/or password, the site takes a few seconds to return and then it ends up being a "Cannot find server or DNS Error" Microsoft error page.  If the user clicks back and re-enters their information continually in succession I've found the application pool become stopped and the page returns "Service Unavailable".  When the correct user information is supplied, there isn't an issue and the user can perform all operations normally.  I'm wondering if there's an issue with the login module on a 64 bit server or if it's a configuration error on my part?

A little helpful information:
The 64 bit and 32 bit servers are only running .Net framework 2.0.
The two servers and the XP instance were setup within hours of each other.  There's always room for forgetting a step, so I went over the installs a few times checking my work.

Thanks in advance!