The game has Tages DRM. Is it some kind of a virus?
Kind of, but not really. Tages is an older DRM that can be very tricky. If you're having trouble with Tages, follow these steps:
Make sure you are running the game with the necessary user privileges — i.e. try running as an administrator via “Run as Administrator” in the context menu of the executable.
Also check your system to make sure you have access to the Tages folder (e.g. the hidden folder “C:\ProgramData\Tages” resp. “C:\Users\All Users\Tages” in Windows Vista and Windows 7, on an English Windows XP this translates to “C:\Documents and Settings\All Users\Application Data\Tages”). Usually this folder will always be accessible to any account, unless your system has been intentionally modified, e.g. folder permissions or ownerships have been changed or there are monitoring tools running on the PC denying access to this folder.