Here is the activity during load and after the page has been posted when you click on the first file in the list.  The URL's in the second part are suspect but I have no idea what to do to fix it.

 

Let me know if there is anything else I can provide!

Load: 
00:00:00.000 0.204 2444 GET 200 text/html; charset=utf-8 /editor/Dialogs/InsertImage.aspx?settinghash=8d635a57
 00:00:00.250 0.219 114281 GET 200 text/html; charset=utf-8 /editor/Dialogs/InsertImage.Frame.Aspx?settinghash=8d635a57&GP=/Constellation/Uploads&C_GP=/Constellation/Uploads&Upload=True&UC=en-US&BG=%23efefef&Th_W=80&Th_H=80&Th_C=5&Th_R=4&MaxW=640&MaxH=640&Resize=True&Restriction=True&MaxImageSize=100
 00:00:00.438 0.000 2048 GET (Cache) text/css /editor/Dialogs/style.css
 00:00:00.438 0.000 2048 GET (Cache) application/x-javascript /editor/Dialogs/dialog.js
 00:00:00.453 0.000 2048 GET (Cache) application/x-javascript /editor/CuteEditorconstants.js
 00:00:00.453 0.000 2048 GET (Cache) application/x-javascript /editor/_shared.js
 00:00:00.453 0.015 413 GET (Cache) application/x-javascript /editor/Dialogs/filebrowserpage.js
 00:00:00.469 0.016 2048 GET (Cache) application/x-javascript /editor/Dialogs/sorttable.js
 00:00:00.547 0.000 8192 GET (Cache) text/x-component; charset=utf-8 /editor/ColorPicker.htc.aspx?culture=en-US&{DNN_Arg}
 00:00:00.547 0.000 31018 GET (Cache) text/x-component; charset=utf-8 /editor/ColorPicker.htc.aspx?culture=en-US&{DNN_Arg}
 00:00:00.563 0.000 556 GET (Cache) application/x-javascript /editor/Dialogs/addvars.js
 00:00:00.688 0.000 31018 GET (Cache) text/x-component; charset=utf-8 /editor/ColorPicker.htc.aspx?culture=en-US&{DNN_Arg}
 00:00:00.703 0.000 31018 GET (Cache) text/x-component; charset=utf-8 /editor/ColorPicker.htc.aspx?culture=en-US&{DNN_Arg}

 

Select the first file in the list triggers this:
 00:00:13.594 0.078 1635 GET 404 text/html /editor/Dialogs/null
 00:00:13.594 0.094 1635 GET 404 text/html /editor/Dialogs/null
 00:00:13.594 0.156 1635 GET 404 text/html /editor/Dialogs/null
 00:00:13.594 0.172 1635 GET 404 text/html /editor/Dialogs/null