Kubuntu installation
The "Default Panel": when accessing "Panel Settings" menu (right click menu), the panel's  min/max width and height can be set here with the mouse, which works fine until you reach a height approaching 1-4pixels, immidiate crash. I am able to only produce this bug when XRender and Raster/Native backends are enabled. Otherwise, the only problem is, the Kickoff panel icon does not update until the mouse passes over it, however, this does not crash the system. in any way   Just the first mentioned - crashes plasma desktop only however it recovers quite quickly, etc.   Another note: this bug could not be reported via automated means because the debug libraries involving it are apprently unavailable (and ive reported before w/o problem).

Reproducible: Always

Steps to Reproduce:
1. Open the Kickoff Panel and go to System Settings and click on it
2. Select Desktop Effects Icon to open dialog, click the Advanced Tab
3. Select "XRender" for the rendering backend and "Raster" for the Qt renderer
4. Click OK and close the System Settings panel
5. Right-Click the Default Panel (Right Click the desktop and Create Panel->Default Panel if you dont have one already)
6. Select the "Panel Options" submenu and pick "Panel Settings" from the menu
7. Click-Drag the "Height" button and move the mouse toward the bottom of the panel, depending on how it is oriented on the screen.
8. As the size approaches zero, the height will keep on going past the snap point (keep dragging). 
9. The Desktop will go black and the Crash Reporting Assistant will immidiately pop up - on low end cards only.

I have tried to duplicate this with other settings with the backend rendering and Qt rendering (Native, OpenGL, etc) and this DOES also cause a different problem, it seems that the panel becomes permanantly garbled as if the inner widgets are mis-sized. In the case of the default panel the garbled size does not recover until kde has been restarted either by a crash or by logging out (or killing+restarting).  This would actually be another bug but I think it may be related to this bug so I am including it here for that reason.
Actual Results:  
On any system that has a high-end video card, this bug does not reproduce. However, I have a wide variety of machines and Only the machines with lower end (cant do opengl effects, etc) have this issue. I pulled my video card and used my onboard video, and confirmed this to be true. 

Expected Results:  
normally, the height will "Snap" to about 8 pixels or so, (depending on the theme and panel contents, i believe)

Workaround
- be careful not to undersize your panel
- keep your preferences backed up 
.... if you do these things, it'll work just fine
Footnotes
I have checked and verified that themes seem to have nothing to do with it. Also I checked to make sure panel contents were at default settings, no special addons or anything could be causing this (to my knowing). The testing machines range from workstation to server. The bottom line is, no matter what, resizing the height of the panel (for me) _always causes some problem that does not fix itself unless kde is restarted_
all machines are on amd64 kernel, ubuntu or kubuntu 12.10, KDE 9.4.9 and all have dual ethernet, >=4GB memory >=10GB HardDiskFreeSpace >=2Cores <=4Cores Intel Core2 processors (either single or dual processors), SATA, 700nhz fsb, DDR2, etc... nothing too special except one is a dell poweredge 1425sc, all machines have DVDrom on them... and maybe more importantly all machines that I have are running WUBI versions of the ubuntu installs, and make use of nfs4, telnetd, samba,tftpd and apache and one is configured as a PXE (DHCP/DNS/TFTPD) server.