When accessing my YAF forum with the full url all is fine, e.g. http://myforum/community/default.aspx

When I try to access the forum using http://myforum/community/ (so leaving off the default.aspx) I get a 'The resource cannot be found' message. The s Requested URL: /community/eurl.axd/59a5a0258d1c614f848ab0322d6901dc/

I'm running IIS 6, and 'Enable default content page' is switched on, with default.aspx (I've tried removig and adding back) in the list.

YAF is running as a Virtual directory under a .NET 4 site. I've broken permission inheritance in the web.config of the top level site so that settings aren't clashing, and apart from this issue all is fine.

Any ideas?