site column "working" in updates taking longer than 15 minutes

Hi, I have a calculated, numeric site column whose formula is quite simple: =TEXT(NOW(),"yyyymmddhhmmss")&RIGHT(NOW(),1).

This column is not being used in any list, is used only in a type content which, by its turn, is not being used in any list as well.

Whenever I edit it and click Ok, it proceeds to the "working" page which never ends. So far I've waited for it to finish as long as 15 minutes, to no avail.