Because this thread started out on a legitimate problem (and has since then seemed to have become a confused mess) I will try and sum up the problem and the only working solution. Thus far, anyway.
The problem is of course that after downloading the installer and initializing it, the launcher appears. Displaying a faded "Start Game" at the bottom right, and various other graphics and bits of text advertising items and so on. All is well, except for the small window displayed in the center, which simply states "The Path of Mabinogi Installation is Invalid". Which is.. Problematic. The entire launcher shuts down shortly afterwards. Having experienced this myself (and tried several things to fix it to no avail), it's a bit frustrating. Nothing even remotely Nexon related has never been installed on this computer before, so delated folder paths that aren't there anyway is a somewhat difficult solution to implement. No Nexon folder was created, yet a Mabinogi folder containing a bug report in My Documents was. I decided to open the bug report, titled 'launcher_log.txt', and was met with this:
Mabinogi Launcher for Mabinogi : ver64
Date/Time : 2008/05/11, 00:54:51
ERROR : CRegistry::GetStringLength(Software\Nexon\Mabinogi,Files) failed.
ERROR : CRegistry::ReadString(Software\Nexon\Mabinogi,) failed.
ERROR : CLauncherMgr::SetGameDir() : invalid path : "D:\".
MessageBox() : #The path of Mabinogi installation
# is invalid.
Cleanup.
Hmm. Exactly where are those directories? And are the commas really supposed to be there? Perhaps an error in the code. But alas, that's nothing I can fix, so instead I take a look at the "D:\" part of the log and realise I have it stored on a secondary drive. Perhaps that's the problem? I switch it over to my 'C' drive, and try again:
Mabinogi Launcher for Mabinogi : ver64
Date/Time : 2008/05/11, 01:11:48
ERROR : CRegistry::GetStringLength(Software\Nexon\Mabinogi,Files) failed.
ERROR : CRegistry::ReadString(Software\Nexon\Mabinogi,) failed.
Game directory is "C:\Users\I Am Admin\Documents\".
MessageBox() : #The path of Mabinogi installation
# is invalid.
Cleanup.
Oh. That didn't help, I guess. In a last ditch attempt, I try and reason where "Software\Nexon\Mabinogi\" would be in my directories, and put the installer there, hoping that perhaps the installer is pointing itself to look for the install files in a certain director, even though.. Well, anyway, I'm sure you can understand it doesn't make much sense, but it's worth a shot. I create the directory "C:\Software\Nexon\Mabinogi,Files" and run the installer from there.
Nothing.
I run it from "...\Mabinogi," and even "...\Mabinogi\Files\" for good measure. Still, nothing. Nothing's installed. Thoroughly confused, I abandon it entirely. Having tried everything I can think of including conventional answers like running it with administrative rights, or shutting off firewalls, I can only blame the program. Or perhaps Vista. But seeing as how others are having the same problem, Vista is off the hook. Like usual.
The only truly logical solution I can think of now is of course downloading an earlier version of the installer that I know works for sure, and installing with that, then updating to the most recent version of the game. Which, funny enough, seems to be exactly the answer found here. So to all still having this problem, I reccomend downloading the FileFront client, and updating from there. I'm downloading it myself, and when it's complete, I'll give my confirmation. (And repost the link.)
I wouldn't bother trying to fix the installer you already downloaded if it's not working. Not until someone from Nexon can come in and explain exactly what the problem is. After all, you probably came to play the game, not troubleshoot it, right? :X
Good luck.
-Mataro.