Sometimes ksysguard (aka system monitor) does not detect that a process has terminated leaving multiple defunct processes on the 'process table' tab. I cannot precisely define the conditions when process termination will not be detected but it looks like 'system load' tab has to be active and that affected programs always interact with X - e.g. mplayer, dosbox and even ksysguard itself. Restarting ksysguard cleans up the process list.

Version 4.7.3 (4.7.3)
Using KDE Development Platform 4.7.3 (4.7.3)
kubuntu 11.10-32

If given a certain amount of time - or given certain events like the starting of certain processes does this change?

I noticed no changes, these lines just accumulate. Even CPU% - if non-0 at the time of process termination, remains the same.

Are you able to try KDE 4.7.4 or the KDE 4.8 RC2 releases?

Sorry, it won't be convenient. But I remember seeing it earlier, before 4.7.3.

I would recommend filing a bug report at this time, as I couldn't find any matching bugs on the bug tracker.

It has already been filed

https://bugs.kde.org/show_bug.cgi?id=261255

This also happens to me on Gentoo with KDE4.8