Rated 5 out of 5 stars

From Xpunged on March 14, 2010
when installing this version I end up in a loop of "this add-on will be installed when Thunderbird is restarted".
I restatart and the message remains.
Any help?
have no choice but to rate you high because I love this addon, it has been a giant help and I know it will be fixed, I just hope soon.
T-bird v3.0.3

I had a similar problem and here's the fix.

Shut down your AV, then install Lightning. Restart Thunderbird and Lightning will work.
Your Firewall or something in your AV is preventing the installation.
The solution worked for me!

This review is for a previous version of the add-on (1.0b1).  This user has other reviews of this add-on.