strange CUPSD and Kprinter activity

Recently I note a lot of cpu activity like the following by CUPSD and kprinter: PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND 1758 root 25 0 14252 13M 12004 R 51.8 1.2 34:56 kprinter 1015 root 25 0 2840 2840 1328 R 43.9 0.2 30:52 cupsd This is the result of top command (note %CPU waste/use). This lasts hours until I decide to '/etc/init.d/cups restart'. Then everything is ok. What can cause this kind of activity that seems to be like an infinite loop? Thank you in advance.