Thank you...yes, it was my bad form/technique that caused the knee problem. In past 2 weeks I have been able to do both excersises without any porblem. I took few sessions with a PT and when I complained the squats and lunges were hurting my knees, he just started to have me aviod them.
Jane in addition to the video that you posted following clips also helped a great deal:
http://www.expertvillage.com/video/3...leg-lunges.htm
http://www.expertvillage.com/video/3...bell-squat.htm
Thanks again for all your help.