Tumbleweed upgrade failed 22-Apr-2012

Upgraded two machines to the latest Tumbleweed status this week-end.

1st machine upgraded without problem, spec,

System:    Host: linux-qz4c Kernel: 3.3.2-1-desktop x86_64 (64 bit) 
           Desktop KDE 4.8.2 Distro: openSUSE Tumbleweed (x86_64) VERSION = 12.1 
Machine:   Mobo: ASRock model: A780GM-LE Bios: American Megatrends version: P1.10 date: 02/13/2009
CPU:       Quad core AMD Phenom II X4 940 (-MCP-) cache: 2048 KB flags: (lm nx sse sse2 sse3 sse4a svm)
           Clock Speeds: 1: 800.00 MHz 2: 800.00 MHz 3: 800.00 MHz 4: 800.00 MHz 
Graphics:  Card: Advanced Micro Devices [AMD] nee ATI RS780 [Radeon HD 3200]     
           X.Org: 1.10.4 driver: fglrx Resolution: 1920x1080@60.0hz, 1680x1050@60
           GLX Renderer: ATI Radeon HD 3200 Graphics GLX Version: 3.3.11566 - CPC
Memory:    DDRII 4GB

2nd machine would not boot up to the gui.
Booting went up to the logon screen as normal, but could not logon.
At each attempt the screen blacked out for ~2 sec. and then returned to the logon screen.
The only way found to logon to the gui was to install the packages, from
Index of /repositories/KDE:/Release:/48/openSUSE_12.1
kdebase4-runtime-4.8.2-370.1.x86_64
kdebase4-session-4.8.2-68.1.noarch

spec. for this machine,

System:    Host: linux-75il Kernel: 3.3.2-1-desktop x86_64 (64 bit) 
           Desktop KDE 4.8.2 Distro: openSUSE Tumbleweed (x86_64) VERSION = 12.1 CODENAME = Asparagus
Machine:   Mobo: TAR model: A880G+ Bios: American Megatrends version: 080016 date: 01/25/2011
CPU:       Quad core AMD Phenom II X4 965 (-MCP-) cache: 2048 KB flags: (lm nx sse sse2 sse3 sse4a svm) 
           Clock Speeds: 1: 800.00 MHz 2: 800.00 MHz 3: 800.00 MHz 4: 800.00 MHz
Graphics:  Card: Advanced Micro Devices [AMD] nee ATI RS880 [Radeon HD 4250] 
           X.Org: 1.10.4 driver: fglrx Resolution: 1680x1050@60.0hz 
           GLX Renderer: ATI Radeon HD 4250 GLX Version: 3.3.11566 - CPC
Memory:    DDRIII 8GB

From what I can see the major difference is the RAM configuration.

From the installed packages only the two packages mentioned about are different.

Has anyone else had similar problems?

Anyone found a FIX?

Happy to recieve and advice.

I had the same problem. I was repeatedly thrown back to the login screen.

It is fixed by clicking the button on the login screen that lets you choose which GUI to access. Choose the Plasma Workspace and you will get in. And that will fix it.

Thanks. Sorted it out.

Thanks!
I managed to start it by choosing KDE Plasma Failsafe, read this and restart using that way.