For years I have used the 'viewsourcewith' add-on in firefox to view and edit html, css and javascript using notepad. Suddenly it only works with cs and javascript, not html. I get the following message when I try to see the html :

viewPage: [Exception... "Component returned failure code: 0x804b000a (NS_ERROR_MALFORMED_URI) [nsIIOService.newURI]" nsresult: "0x804b000a (NS_ERROR_MALFORMED_URI)" location: "JS frame :: resource://vsw/common.jsm :: ViewSourceWithCommon.makeURL :: line 77" data: no]

I know this is a javascript forum but the top of the dialogue box says 'javascript application', suggesting the problem is something to do with javascript.

Anyone got any ideas why this is happening?