Yes, I do defragmentation from time to time (every 2-3 weeks). Last time I did defragmentation few days ago, but I could do it again, so I will today.

The funny thing is that I have been normally using my computer a couple of years, always with the same configuration - Windows XP with simple programs like Opera browser, Office, Adobe Reader, Skype, avast etc. And for this couple of years my PC was working like a flash, everything has been loading with normal speed and I never have problems.
How is that possible that suddenly now it stopped working the normal way it was? Could it be a hardware issue? I don’t know, maybe my RAM is damaged (can it be damaged?)?