I started a new install of etch in a VMWare 5.5.3 (running itself in an etch-environment) and directly after a minimum installation (nearly no packages selected) I changed in /etc/apt/sources.list all "etch" to "lenny". After apt-get update && apt-get dist-upgrade (both without any errors), I can't reboot with the 2.6.22-3-686 kernel, the problem is with the root-filesystem. Depending on the package I create the initrd with, the system just writes "Waiting for the root filesystem" (or similar) or is waiting for 1, 2, 4, 8, ... seconds (yaird).
Before, I downloaded the current netinstall of lenny with amd64 (above installation is i386!) and I had the same problem on first reboot.
Both installations were started last weekend (15/16 March 2008). With the current install, I can still reboot with the etch kernel.
I made an etch-to-lenny installation the same way some months ago in a VMWare environment running in windows. This installation is still running without any problems. I don't see the difference. What am I doing wrong?

Whoever might be interested: it seems to be a problem of VMware. I upgraded to 6.0.2 and the 2.6.22 kernel booted without any change.