Hello everyone and thanks for your time.
Things I've tried:
- Health check - Everything was OK (PHP version 5.2.14 and MySQL version 5.0.91)
- I disabled all the plugins. - No effect
- Manual Installation. - No Effect
- TwentyEleven theme. - No Effect
I tried with Chrome and Firefox and it was not working... but in Internet Explorer is working fine. I have all the browsers up-to-date.
I really appreciate your help in advance :(