It looks that my system is hacked

Hi every body,

Yesterday my computer failed to start I got an error message saying that it can not login and then nothing was displayed on the screen although my computer seemed to run!

Few days ago, when I turned on my computer all my files were erased and then few hours later they were all back!

I know it's a bit weird, but I know that some (rascals sorry for the word, including my ex thesis supervisor who through another student nicknamed PAB threatened me that I won't get my degree until he has not decided are teasing me because they're fishing for God knows what!) students harass me which is why I thought that they could also be hacking my comuter for example copying my data saving them, erasing them from my computer then pasting them back! which is very reasonable in terms cyberharassing!

Can you give me hints as to how I can detect such infiltrations and how one would copy paste data in such a way!
thanks alot!:cool:

The Dude