I now experienced that the system clock of my PowerBook 12" runs too fast. I'm adjusting it nearly once an hour using ntpdate now and it seems to change about +1m per hour. I hope this isn't a hardware problem.
No, the kernel is making up for the hardware clock which he *thinks* is
going 1m per hour to slow.
Empty your /etc/adjtime and then update your hwclock once(!). Then wait
a week or two before you do it again. The difference between the real
and the hwclocktime is then stored in the above mentioned file so the
kernel can correct it, given the drift is constant, which it normally
is. You probably set the hwclock two or more times in a too short
periode of time ("Viel hilft viel" ;-) so a wrong drift was calculated.
See 'man hwclock' /NOTES for the complete story.
If the clock is too wrong while your are waiting for a second correction
run # ntpdate <server>; hwclock --systohc --noadjfile (+ --utc maybe).
HTH
-Thomas