external application firefox%s required?

Suddendly when trying to open any second page as default user, the following alert pops up:

External protocol application request

An external application must be launched to handle https:links
requested link: https://launchpad.net/ubuntu/edgy/+source/firefox/+questions

Application: firefox %s

If you were not expecting this request it may be an attempt to exploit a weakness in
that other program. Cancel this request unless you are sure it is not malicious.

Remember my choice for all links this type

cancel launch

The same is also for any link, then it says: An external application must be launched to handle http:link

I did not want to lauch such application so I made for myself a new profile, and it solved the problem but naturally this is not the right solution...