How do I avoid my ~/.kde/tmp-sda2-enc/.kio_thumbnails* using all my free space

[user1]

I am using 10.04 encrypted installed on one partition of 30 gb and 
suddenly the partition ran out of free space.

Then I ran "filelight /" and it showed that my 
/home/username/.kde/tmp-sda2-enc/thumbnails* was filled with some 10 gb 
thumbnails in various folders.

How do I avoid this directory filling up again probably emptying it after 
every shutdown.