We're running a site on 4 virtual Win 2008 R2 64 bit servers.

This is the only site on the IIS, and we use Windows Network Load Balancing to share the load between our 4 virtual servers.

We've used these virtual servers for approximately a week, and we're starting to see some issues.

For no apparent reason the IIS stops serving pages, and doesn't even respond with an error. So upon requesting a page from the server, the browser just waits infinitely (or until it decides to give up clientside)

Sometimes an iisreset fixes the issue, other times we have to reboot the entire virtual server.

There are no traces in the eventlog of why this happens, and there's no traces in our applications exception log neither.

Furthermore this happens even when there's a very small load on the server, so it doesn't seem to be because it's flooded with requests.

So frankly I'm at a loss here - I have no idea where to start debugging this issue :-(

I'm quite certain we never had these issues on our physical servers, however they were running Win 2003 32bit, so there are quite a few differences between them and the virtual ones. (Which obviously makes it difficult to tell what exactly causes this)