This seem to be a wide spread problem:
DCOM SErver Process Launcher Service Terminated Unexpectedly. The shutdown is done by NT Authority/ System. Shut down in 60 seconds.
There are several reports in the Microsoft forums (and the rest of the Internet):
windows shuts down unexpectedly
DCOM SERVER PROCESSOR
Apparently this error message is a symptom of the computer being infected with malware. And the popup only seems to come when the computer is connected to the Internet.
The solution is first to stop the computer from rebooting. This can be done by executing this command from a command prompt (cmd.exe) with administrator rights:
shutdown -a
After having prevented the reboot (using the above command), then one should visit an online virus scanner to remove the malware:
Windows Live OneCare safety scanner
TrendMicro Housecall
One should also make sure to update Acrobat Reader and Adobe Flash, as older versions has security holes that the malware uses to infect the computer.
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