Are you by any chance using Panda Security?I just downloaded and started the game to test it out.
Right after starting my security software blocked a suspicious file and moved it to quarantine.
Now it demands a reboot to finish up the removal of the remaining malware.
That software is usually correct and has not produced a "false positive" in well over a year.
It is possible it just did, though.
And could you tell me what file it was that got flagged as suspicious?