I do not know what happened but I have lost all my ArcToolbox log history that was available trough "Results" menu.
The strange thing is that I can access the log files that are saved on my harddrive. Those files are on .xml format but I do not know how to import them back to the "Results" history menu.
Can someone give me a help on this? To me is extremely useful to see the results history! It helps me a lot!