I'm pretty sure I've narrowed this down to a bug with the PA version of TBird. It's crashing whenever I try to load in a new extension, in this case the Lightning and Google Provider extensions. I haven't been able to replicate it in the desktop version of TBird 24 that I downloaded directly from their website. That seems to work fine in Win7.
What happens is I go to Add-ons-->Install Add-on from File, then navigate to the .xpi file, the entire app freezes up when I hit 'add'.
Addendum: I've tried this on two different Win7 machines with the same results.
this is often a problem with some extensions.
However, what you should try first is to let is be 'frozen' for some time. This can take number of minutes and it will cure itself finally.
In some cases I had even to copy the Thunderbird to the hard drive and do the lightning installation there and then copy all back to the usb stick. Doing all on the usb stick took otherwise very long time.
Thanks. I tried doing this on two different Win7 desktops, and I'm still getting the error. It just seems to freeze up everything, and it tells me that a script has stopped working. This only seems to happen with the PortableApps version and works fine on the Mozilla desktop version.
Ok, after the third fresh install, I got it to work. I'm really not sure what happened on the first two, though. Weird.