Version:           4.2.00 (using KDE 4.2.0)
OS:                Linux
Installed from:    Debian testing/unstable Packages

When a window is closed and I attempt to switch applications while that process is handled Kwin crashes

I have this primarily with GTK applications (Synaptic opens and closes windows automatically when updating or installing, for example), but it's possible it happens with Qt ones as well. GTK applications are a bit slower, while Qt ones close nearly instantaneous, which might explain why I have this problem only with GTK applications.

Kwin respawns after crashing, which is quite nice, considering opening and closing windows can happen a lot during a session.

I got this backtrace (it's... err... rather short):

Application: KWin (kwin), signal SIGSEGV

Thread 1 (Thread 0xb63ff700 (LWP 5772)):
#0  0xb7f08424 in __kernel_vsyscall ()
#1  0xb7d7bed0 in nanosleep () from /lib/i686/cmov/libc.so.6
#2  0xb7d7bd0f in sleep () from /lib/i686/cmov/libc.so.6
#3  0xb7ba0128 in ?? () from /usr/lib/libkdeui.so.5
#4  0x00000000 in ?? ()