Problems to connect to Internet

I’ve installed openSUSE 11.0 a few months ago and it used to work find.
But two weeks ago it began to have troubles to browse Internet: With Firefox, for example, each time I want to open a site, appears the site couldn’t open. (Sometimes, after I insist several times I get to open a page.)
Also, I have problems to search updates and with all applications use Internet.
I re-installed Firefox but the problem is the same.
I think no configuration was changed.
I test my connection to Internet from Windows, and it works fine.

Any suggestion?
Thank you in advance.

I beg your pardon.
I think It was a problem with my router.
Thank you, anyway.