António Silva:
I forgot to say that my problem have a slight difference because to me this happens with RSS Portlet that come with Liferay 6.1.
I will see what you say in RSS Portlet source code.
I can reproduce it with a RSS Portlet installed.
Lowest layer of call stack is "IO._rS" from "io-base.js" (onReadyStateChange event handling),
but i can't directly see a solution to this problem.
But i think a browser who runs with production code should never caught exceptions.
Don't know if IE or other can handle this, i use Chrome and can set this in the debugger.
Are there side effects in your case?
Keep on coding
André