Cannot properly view another person's webcam
 

I've just installed a webcam of my own, after a series of problems to which I got lots of answers, it works just fine now (I use Ubuntu Edgy and Kopete as instant messenger).

But now I have difficulties in viewing another person's webcam. Either of the 2 situations below occur:

1. I receive the error message: "Webcam of X is not available"
2. I start viewing the other person's webcam, but after a period ranging between 1 to let's say 50 seconds the image "freezes".

Either of the 2 situations occurs at random, and if I do start viewing the other person's webcam, the period after which the image "freezes" also varies at random...

What can I do? Thanx!