Avast won't update

[citizen]

I've had Avast downloaded for a few months (since around February, and no I'm not using the outdated version) and it has worked and updated fine.  A few days ago I got the message that there was a problem updating, saying:

Information about current update:
Last encountered error: Can't select any server for downloading (from 0).

Total time: 0 s

I ignored it at first, figuring that the next try (happening the next day) would work.  However it didn't, and it continues to give me the error that it can't select a server.  I've tried to make sense of what it's telling me (as little as I know in this area of computers), but all I can come up with is that it doesn't know where to download from (that "from 0 part)?
So, I looked in the FAQ's and saw that it said to check to make sure my firewall (Windows, for me) didn't have it blocked.  I checked and sure enough, it wasn't on the exceptions list.  So I placed it on and hoped for the best, trying again.  However, it still gave me that same error, so I'm at a loss of what I'm supposed to do.
Thanks for any help anyone may give.

[DavidR]

The servers.def file would appear to be corrupt or 0KB, C:\Program Files\Alwil Software\Avast4\Setup\servers.def . You can try and download the servers.def file, http://files.avast.com/iavs4x/servers.def and rep[lace the original.

[citizen]

Well that fixed it.  I had to do a search for it after downloading that link you gave me, as it was hidden (being a .def file, and all...), so seeing it was in the setup folder I saved it into that, chose yes to replace it, and ran the update again.
Thanks for helping!

[DavidR]

Glad I could help, welcome to the forums.

You might want to ensure that hidden files and folders are displayed, also uncheck Hide extensions for known file types, in windows explorer, Tools, Folder Options, see image.