...nothing i have hit cam my name too? i have clicked on cam i have ckicked on ok to see and just get a box that say waitin on them to say ok have they have ask me to see them some have tried many times when i hit the x to close after a bout 5 mins message closes and i have to restart my computer ty you for you time says program has done something wrong and i have to sign back in on computer

You might not have the same yahoo version or the other person just don't really want you to see them.
About messenger closing after you close webcam, might be that your computer is low on resources. Close other running programs you don't need.
I heard this messenger closing has happened to many. Just log back in.