Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

• Don't make any changes on the Safe mode start window.

See:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems
• Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

See also:

• http://kb.mozillazine.org/Corrupt_localstore.rdf

Safe Mode did not bring anything new to light. However, I did notice that a few people have posted on the KAT Community forum that they are having this problem with .torrents downloaded from that site, while most other downloads seem to function as expected. I experimented and found that this strange behavior is limited to downloads from KAT and other sites seem to work as expected for me, as well..

I guess that means that the issue is with KAT and not FireFox.

(sigh)

Is there a way to test exactly WHAT it is about downloads from that particular site are behaving badly?

The"Safe Mode" solution does not help. Nether does turning off extensions. Is there another way to find out what the interaction is between the KAT website and Firefox that is different and causing the problem?

bump......

I'm wondering why there is no action here. I have checked my "applications" area of my Firefox preferences. I am now on Firefox 4 by the way. I went to the torrents file type and I saw that the Vuze application was showing. I deleted it and selected it again. Quitting and restarting Firefox along the way. Still no joy. I still get a small dialog box that requires me to save the torrent file to my downloads folder and then find it there in order to double click on it to kick off Vuze, instead of Vuze being preselected as a choice in the dialog box, which would then kick off Vuze right away like it used to.. This is a real pain since Firefox was originally able to do this intelligent action quite reliably.