Upgrading Kubuntu to Version 7.10 crashed

[gesslar]

Binary package hint: update-manager

When upgrading to 7.10, I got the following message:
Upgrade Tool Crashed
We're sorry; the upgrade tool crashed. Please file a new bug report at [url].

Traceback (most recent call last):
  File "/tmp/kde-root/adept_managerYkoo4b.tmp-extract/dist-upgrade.py", line 59, in <module>
    app.run()
  File "/tmp/kde-root/adept_managerYkoo4b.tmp-extract/DistUpgradeControler.py", line 1346, in run
    self.fullUpgrade()
  File "/tmp/kde-root/adept_managerYkoo4b.tmp-extract/DistUpgradeControler.py", line 1328, in fullUpgrade
    if not self.doDistUpgrade():
  File "/tmp/kde-root/adept_managerYkoo4b.tmp-extract/DistUpgradeControler.py", line 798, in doDistUpgrade
    res = self.cache.commit(fprogress,iprogress)
  File "/tmp/kde-root/adept_managerYkoo4b.tmp-extract/DistUpgradeCache.py", line 69, in commit
    apt.Cache.commit(self, fprogress, iprogress)
  File "/usr/lib/python2.5/site-packages/apt/cache.py", line 203, in commit
    res = self.installArchives(pm, installProgress)
  File "/usr/lib/python2.5/site-packages/apt/cache.py", line 178, in installArchives
    res = installProgress.run(pm)
  File "/usr/lib/python2.5/site-packages/apt/progress.py", line 213, in run
    pid = self.fork()
  File "/tmp/kde-root/adept_managerYkoo4b.tmp-extract/DistUpgradeViewKDE.py", line 244, in fork
    self.child_pid = os.fork()
OSError: [Errno 12] Cannot allocate memory

=================

gesslar@lxsrv1:~$ df
Filesystem Size Used Avail Use% Mounted on
/dev/sdb3 69G 29G 37G 45% /
varrun 252M 268K 252M 1% /var/run
varlock 252M 0 252M 0% /var/lock
procbususb 252M 152K 252M 1% /proc/bus/usb
udev 252M 152K 252M 1% /dev
devshm 252M 0 252M 0% /dev/shm
lrm 252M 33M 219M 14% /lib/modules/2.6.20-16-generic/volatile
/dev/sdb1 3.8G 121M 3.5G 4% /boot
/dev/sdb4 74G 48G 23G 68% /home

I have plenty of memory, I don't know why it would be crashing. I have 512MB.