Debian dist-upgrade: Laptop suspends 30s after boot / startup

After i moved to jessie (Debian 8) my laptop moved to suspend to RAM about half a minute after startup.
There was no message in the logfiles and even worse the resume does not work at all...
The configuration for the suspend was in here:

/etc/systemd/logind.conf:
 [Login]
#NAutoVTs=6
#ReserveVT=6
#KillUserProcesses=no
#KillOnlyUsers=
#KillExcludeUsers=root
#InhibitDelayMaxSec=5
#HandlePowerKey=poweroff
HandleSuspendKey=ignore
#HandleHibernateKey=hibernate
HandleLidSwitch=ignore
#PowerKeyIgnoreInhibited=no
#SuspendKeyIgnoreInhibited=no
#HibernateKeyIgnoreInhibited=no
#LidSwitchIgnoreInhibited=yes
#IdleAction=ignore
#IdleActionSec=30min
#RuntimeDirectorySize=10%
#RemoveIPC=yes

After changing the lines "HandleLidSwitch" and "HandleSuspendKey" to ignore and one more restart the laptops stays alive and no unwanted suspend is happening anymore.
That was a strange behaviour, because my first guess was overheating. But after waiting 10 minutes the laptop was really cool, so overheating was not the point...