If your Xubuntu 8.x/9.x (XFCE) VM keeps logging you out on startup it may be a problem with your XFCE config startup or VMware tools toolbox startup settings.
So just reboot your VM into single user mode or login as root (only if you’ve pre/re/enabled root account login) and goto the users directory that has the problem and :
# cd ~user-with-problem
# mv .config .old
Now you should be able to re-login as then problem user !
However they will have lost all their XFCE X11 X settings but you can now :
$ diff -qr .config .old
to investigate the XFCE or VMware setting that was causing the problem !
You can also check your .xsession-errors file(s) to see if you’re getting:
vmware-user: could not open /proc/fs/vmblock/dev
in which case you could try and re-run vmware-config-tools.pl and reboot to fix !