Thank you very much Sami, those sites linked were really useful. They are indeed EXPERTS.
Yesterday, I spent the whole day running all the procedures suggested. Now, having no had the expected results, I will post the logs results on their forum to see if they can give me some solutions.
Another thing that I discovered after running the cleaners, was that my copy of Windows seems to be not genuine...
I'm getting a warning on the lower right of the screen. Unfortunately, the shop where I bought my PC has closed more than a year ago
The PC still working at slow motion and the old hangs-up still occurring two or three times a day...
I will travel next week, so I'm kind of busy to manage this situation right now, even though, I think that there wont be too many solutions to choose from.