How to fix unarc.dll or Isdone.dll errors?

Whenever I’m downloading any archive from the Internet and trying to unpack it, or install it, for example a game or so, with the help of installation program I am facing Inno setup errors like the “unarc.dll” and “Isdone.dll”. I want to know the reason and solution to it. Please help.

ISDONE.dll
An error occurred when unpacking!
Unarc.dll returned an error code: -1
ERROR: archive data corrupted (decompression fails).
