I am running Lightning without problems so far on Vista Ultimate 64-bit.
I am also running Firefox V3.0.1, also without problems. However - when I open Firefox, there is a note that the newly installed Lightning extension is not compatible with Firefox 3.0.1.
I see other posts on this site going back to 2007 with Firefox problems. Firefox is now over 18% of the browser market. Lightning (which I received with my newly purchased WordPerfect Office X4 - [I have been a WP user since V4 back in the 1980's]) seems like an excellent product, but this forum site seems to be getting very little helpful response for the users attempting to get help with this problem.
From the dating I see, it would seem that there have been no updates to the product for nearly a year since a check showed no responses to my request for updates, and my current version of Lightning was built in Sept 2007. I see that the Firefox extension in the Lightning file area is dated back to April 2007.
Help? Any time soon?