This is a problem that's been off and on (mostly on) for me for a week or so.
When I try to edit a listing or Create from Similar from the Saved Listings page my browser (Firefox) crashes. It doesn't bring anything up, just goes blank and freezes up (all tabs). As far as I know this is a new problem although I never did much editing from Saved Listings until recently. Clearing the cache doesn't seem to help.
This same thing happens occasionally (though not as often) when I try to Error Check a listing I'm working on.
Just to clarify, if I Create from Similar using the dropdown on the main Listings page, I have no problems at all. If that dropdown was populated with a much longer list I'd just use that.
I can usually work around it but it sure would be nice to be able to use this feature.