I killed my install the other day with a botched update. Before reinstalling, I backed up my home directory then started a new install of Arch, and upon basic completion I copied all of my files back.

First, I noticed I had a file called "os,sys" (that is a comma, not a period) in my home directory that I don't recall it being there before --it may have been, but I don't remember. Next, I noticed that yaourt will not function, giving me this error:
==> Installing from a package list
error: '%%HiResBoundingBox:': could not find or read package
I thought the two were unrelated until I happened to open os,sys as a text file. It's a huge file but it starts with this:
%!PS-Adobe-3.0
%%Creator: (ImageMagick)
%%Title: (os,sys)
%%CreationDate: (2011-01-07T15:51:02-06:00)
%%BoundingBox: -0 -0 1024 600
%%HiResBoundingBox: 0 0 1024 600
%%DocumentData: Clean7Bit
%%LanguageLevel: 1
%%Orientation: Portrait
%%PageOrder: Ascend
%%Pages: 1
%%EndComments
As you can see, line 6 contains the HiResBoundingBox mentioned in the yaourt error. But ultimately I'm still lost. Any clue what os,sys is, where it belongs, and why it may be bothering yaourt?