the connection with the server was reset

We recently upgraded our IIS5.0 to IIS6 as part of our upgrade to Server 2003.
Ever since then, we get the above error when trying to download a file (6.99mb).

About 75% complete and the download shuts down. We can resume it and the download finishes.

Our timeout settings are at 20 minutes and the above happens within 1-2 minutes after download start...

Any thoughts?

Not sure, I've had people download/send files in excess of 100 megs over iis6 without a hiccup. I would remove IIS from the server and reinstall it to make sure that there are no permissions issues.