A mas to vsetko legalne a neposkodene?
https://battlelog.battlefield.com/bf3/forum/thread view/2832654347968640680/

The NSIS errors may occur under one of the following conditions:
1. Software files downloaded from the Internet are not complete.
2. Downloaded software files have been modified from the original version.
3. Your PC is infected with a virus.
4. Physical media being used to install the program is damaged.
5. Required hardware (For example, CD/DVD drive) is malfunctioning.