Thanks Adept, for providing useful hint.
Actually, what I did was, I started removing one by one, the new fonts which I had recently installed. The "Access Denied" error popped up for three of them. So I restarted the machine in "MS DOS Mode", removed those fonts, and rebooted. Voila!! Everything is in place now!! No more junk characters in OE or other software.
Once again thanks a lot everybody.
It's very nice when problems get solved like this sharing the thoughts! May be one day, I will be able to help somebody like this.
Regards.