zombi process on kde 4.6 rc2

i have kde 4.6 rc2 on my kubuntu maverick.

after many hours from startup of kubuntu, i found a lot of zombi process.

for example:
i start dolphin, after i close it..
After 30 min i reopen dolphin and it doesn't start.

i show run process and i see that i have 2 dolphin process:
1 is the process that i try to start
the sceond is a zombi proces

i have also 2 kded4 zombi

simone@laptop:~/.kde/share/apps/nepomuk/backupsync/backups$ ps aux | grep kded

simone 1546 0.1 1.1 262660 48856 ? Sl 14:19 0:30 kdeinit4: kded4 [kdeinit]
simone 1891 0.0 0.0 0 0 ? Z 14:19 0:00 [kded4] <defunct>
simone 1896 0.0 0.0 0 0 ? Z 14:19 0:00 [kded4] <defunct>
simone 11647 0.0 0.0 3484 756 pts/1 S+ 21:24 0:00 grep kded