^M at the end of every line in vim
One easy way to strip out the DOS line endings is to use the ff
option:
:set ff=unix:wq
Now your file is back to the good-old-Unix-way.
If you want to add the DOS line-endings (to keep a printer happy, or transfer files with Windows friends who don't have nice tools) you can go the opposite direction easily:
:set ff=dos:wq