SSD filled until it's full

Dear Fedora users,

I have an annoyig issue with my fedora 17 KDE spin.

I have an 258Gb SSD drive filled with around 65Gb of useful data (193Gb free). When I switch on my computer, linux slowly fills the SSD until it's full. It takes about 12 hour to fill the SSD. I have to reboot the computer to retrieve the 193Gb of space.

I don't know how to find in which file or folder goes my free space...

Marcel