I installed ubuntu 14.04 about 2 months ago and about 1 month ago this issue began to occur:
Whenever HDD is used (saving a file, file download, opening a file..even small ones) there is about 60% chance that computer freezes for about 20 seconds. I can move mouse, but nothing reacts. When I turn on mySQL server and apache and browse hosted web, it freezes really often.
I don't recall installing anything special that month ago, which could cause this. Before that, I had ubuntu 12.04 and everything was fine. My RAM is only half full and the application for testing a system didn't show anything.
I am on a Lenovo Z570 notebook, i5 dual core CPU, 4 GB RAM. One physical 750GB disk, three NTFS partitions (I have dualboot with windows) and the linux filesystem.
Any idea, what might cause this? Thank you very much for any help!
EDIT: few new things: It seems that this bug applies only to the Home folder and subfolders. Whenever I create, copy or delete file or folder, everything is fine for 3 seconds and then the HDD starts spinning and everything freezes for 20-30 seconds. I remembered, that maybe that month ago a friend changed some config files so that my three partitions would attach during the boot. Maybe that could have caused this issue, but can't tell for sure.
Screenshot of System monitor: