Finally I solved my plugin problem as well as my Firefox bug problem.
This was creating the problem. Also I changed the owner settings for my wordpress which results in letting me download and upload plugins directly from my Dashboard.
The second problem was that of Firefox browser. My wordpress site was not showing correctly on my firefox browser but was working on all other browsers (Opera, Chromium and Arora).
This was due to incorrect header setting in style.css file of my theme. Firefox wasn’t rendering the header area correctly and the primary menu bar was showing over the logo. I thought I should integrate Mozilla web-kit to make it work. I was pulling my hair out since last few days to figure out the problem but wasn’t so successful till today. So by changing the default header height value to large number I solved my problem.
Its a big relief that these problems are now solved.
Lets see what tomorrow brings!