Sometimes I get a 404 error returned from the server when making a request to a module other than the default module (I am using the conventional modular layout). The error does not occur often, once every three weeks or so.

The web server is running IIS 6, and I am using a pretty standard Isapi_Rewrite rule. The 404 from the server suggests to me that for some reason the request is not getting sent to the bootstrap file for all requests to modules other than the default.

IIS logs just show a 404 error as expected, and the Windows Event Viewer does not show anything.

I am currently using ZF 1.5.2, though this has always been an issue.

Closing the browser and reopening the browser fixes this seemingly random problem, until it occurs again.

Any thoughts?