Overture problem after patch

[AnUub1s]

Hello,
i´ve got my copy of Penumbra: Overture from the
czech gaming magazine "Level" (not in english sorry) issue 157 March 2007,
the game wasnt runnig because of some odd error so i didnt play it,
now nearly one year after i bought the game i instaled the (actual) patch hoping that the game will now run
but sudenly the game wants a serial key from me even though i didnt need
one before and i didnt get one with the game (before the patch i could start the game i heard the menu music but the the game crashed afterward).
thx 4 any hlp

PSorry for any grammar issues