Not sure where Djoni Filho is so I thought I would chip in with some testing for you to do, see below;
Try removing the battery and booting up with only the AC adapter connected, what happens, remove the AC adapter, replace the battery and boot up, again let us know what happens.
If you have 2 sticks of Ram try removing the stick in slot 2 and boot up, make a note of what happens, shut down and swap the stick into slot 2, boot up and again make a note of what happens, repeat the process if you have a second stick of Ram.
Run the HDDs diagnostics tool;
Make sure you select the tool that is appropriate for the brand of your hard drive http://www.tacktech....ay.cfm?ttid=287
Depending on the program it'll create a bootable floppy or a bootable CD.
If the downloaded file is the .iso type use ImgBurn: http://www.imgburn.com/
to burn the .iso file to a CD (select "Write image file to disc" option) and make the CD bootable.
Let us know the results of the testing when done.