I recently downloaded the game client to play RO and quickly got frustrated by that sporadic No ClientInfo File error. I had tried many of the "solutions" found here or elsewhere to no avail. Reinstalled many times, repatched many times, no anti-virus active, run as admin, etc etc...
While reading an FAQ yesterday however I found this on irowiki.org:
Q: The patch server is down, can I play without patching? Yes, it is possible. To start the game and bypass the patcher, you need to start the game with an argument. Either from the command line or a shortcut, append to ragexe.exe "-1rag1" for the main servers or "-1sak1" for Sakray. Command line example: C:\Programs\Ragnarok Online>ragexe.exe -1rag1. Shortcut example : "C:\Programs\Ragnarok Online\ragexe.exe" -1rag1 (with the quotes). However, without the latest patch, the game client stability is not at its best.
So here is the solution for all of you with the same problem (until this patcher is fixed). As stated in the quote, first make sure your client is properly patched (you should have no problem patching it). Then create a shortcut (anywhere) of the ragexe.exe file. Right click on it and select Properties. At the end of the Target input box, simply append (after the double quotes) -1rag1. Save.
Enjoy! HTH.