I had to change my working environment to a new machine where I had to reinstall all the needed software again. At that time I ran into a great trouble in installing FireBug to firefox. Whenever I installed it it ask me to restart but when it gets restarted there s no FireBug installed.
I tried many variation that was available online spend a long time in figuring out that. Tried with many version of either software, shagging the profiles ect… but nothing worked out or not error messages were given. Finally I tried with disabling the virus scan (mine is kaspersky). Luckily at that time it worked fine.