Thank you for your reply BC_Programmer, and specially for the last paragraph
I purposely tried to avoid using "electrical failure" in my previous posts and used "electrical troubles" because there was no electrical surge, lightning nor power supply short (at least not at the wall outlet level).
This is how things occurred:
After trying unsuccessfully to follow the Blue Screen indications the computer began to boot into Windows and I was able to access my account but a Microsoft Windows Error Report appeared. While I was trying to follow its suggestions, XP's updates download progress bar froze on the monitor . The same happened with the mouse cursor and there was no response to the keyboard input.
Each time I rebooted the computer, the same thing happened.
At a certain point I also heard a sort of muffled snap sound so I opened the cabinet, looked inside and smelled but everything seemed right.
Because the monitor was still frozen I rebooted the computer.
This time I wasn't able to boot into Windows so I decided to access the HDD through a Linux Live CD I have.
So I started the computer with the Live CD on the CD-DVD drive.
The screen showed the Linux files were being copied to RAM but at a certain point it stopped and the cursor remained flashing indefinitely on the screen.
I tried to reboot the computer but there was no response.
I tried to shut it down and there was no response so I unplugged it from the wall outlet.
After 15 minutes I plugged it back and restarted the computer. It was there where I discovered the fans worked, but the blue light on the "on" button of the cabinet didn't work and there was no screen response.
It was here where I decided to consult the technician.