Visit
http://www.spychecker.com/program/hijackthis.html and download the hijack this zip file.Then open the file.It will tell you what is on your PC,and what can be deleated,in case of conflicts.
Whether it tells you your web cam can not talk to AOL or MSN Messinger,or both,I don't know,but AOL certainly crops up a lot on this forum.
As a footnote,if Internet Explorer is causing you problems,download Firefox if you have not already done so.
If all else fails update the driver files for the web cam on both pc's.Check for hardware,or software conflicts.
Best wishes,
Nez :)