Webservice and Url rewrite help

I have a webservice in the root of my solution, but whenever I try to call it, the url rewrite mechanism append the default "/default.aspx" in front of the webservice.

Ex:
http://<domain>/Autocomplete.asmx/GetCompletionList/default.aspx

Should just be:
http://<domain>/Autocomplete.asmx/GetCompletionList

Can I add some sort of ignore rule in the url rewrite config, and if so how ??