[Intrepid] KDE4 BSOD/Black Screen

[NoOp]

Ran into an odd, or perhaps not so odd, issue w/Intrepid today; whenever
I log into KDE(4) I get a BSOD - black screen with working KDE4 mouse
cursor.

I say 'odd' as I seem to recall that this worked OK (albeit with the KDE
oddities/problems of KDE4 in general) just recently.

Note: I always use gnome but have KDE installed for testing.

Thinking that it might be related to the latest kernel update (in my
case 2.6.27-10 as I have the proposed repository enabled) I tried
booting to the older 2.6.27-8 kernel: no change.

So, given that this is a vanilla test machine and the fact that I
originally had installed KDE4 via a ppa, so I went through the following:

1. Renamed .kde and .kd4 - no change.
2. Removed/purged KDE/kubuntu using
http://www.psychocats.net/ubuntu/puregnome
Rebooted & checked the system afterwards in Gnome, all well.
Note: I previously had kde4 installed via the ppa, hence the reason to
purge all. Reinstalled kbuntu-desktop (sudo apt-get install
kubuntu-desktop) - no change - BSOD.
3. Booted into recovery mode and tried option 4 xfix - no change - BSOD.
4. Booted into 2.6.25-2-386 - no change - BSOD.
5. Booted into 2.6.24-21-386 (hardy kernel) - works!

This is an old Thinkpad A21M that had KDE4 working in hardy, so no
special compiz et al., just standard intrepid update from hardy. So
what's up with the intrepid kernel(s) and KDE4? Anyone else experience this?