I also have the dreaded Error 8504,104 with Norton not starting up. I did uninstalled and restarted numerous times. Went to support and did the Removal tool and the eraser. The Eraser found no problems. I did restart each time. When I went back to Norton webpage to install again the page says it's installed but the indicator is still spinning "installing". This has been going on since beginning of April. Had surgery so not able to sit very long. After I did remove Norton with removal tool, Internet Explorer will not open. I haven't even tried getting my firefox back as I believe it all started back when I had to reload firefox and ended up with vosteran! Help!