Bad Request <OR> Illegal characters in path

Here is my issue:

1) This is an ASP.NET 1.1 website hosted on Windows2003 Server
2) SP1 for .NET 1.1 is installed
3) I have the .gif extension mapped in IIS to the 1.1 aspnet_isapi.dll
4) I have an httphandler configured for the website:
<add verb="*" path="*.gif" type="myNamespace.myHandler,myHandler"/>

When I make this request:

I get an error:
HTTP/1.1 400 Bad Request - Bad Request

I then added a registry key as described here:

When that registry key exists the error changes to:
HTTP/1.1 500 Internal Server Error - Illegal characters in path

Is there any way to remove the HasIllegalCharacters check so that my handler
can receive the request?