sfdxsm: I don't have a steam account and found out Steam hates my PC but I'll keep that in mind too for when March rolls around. ^^ Tho I seem to remember Steam messing up existing installs.
I don't believe the problem lies within steam. The error message you're referring to is probably the "The version update failed: Failed to replace Polhook.dll" problem. I recently installed the game via steam to a fresh windows OS and had that error pop up, but I did some research on google and it appears it's happened infrequently since back in 2004. There's a few threads that report the error on several sites, one of which is BG back in the ToAU era. The problem happens when the playonline viewer installs for the first time on your system (or what seems to be exceedingly rarely after a POL version update occurs). It detects that there is an updated version available, but it sounds like when the first version update happens the registry fails to update a pointer or something. What you have is two physical copies of the Polhook, which is the link the game uses to launch the playonline viewer. One is the old version of the file, and one is the new version of the file. One of the web sites suggests a fix that you simply delete the old version and replace it with the new version, but that didn't work for me. Instead I just uninstalled the program and reinstalled it. I got the same error again but after opening the playonline viewer once or twice it seemed to resolve itself. The error isn't a permanent problem, and seems to be fixable with just a few reiterations of opening and shutting the program. What's ironic is that I ended up resetting the operating system back to its factory state the next day just because it didn't have anything important on it yet and tried the install from scratch. The second time it worked just fine and the error never popped up. Both times were right after a fresh steam install, so it's not on their end but something in the playonline viewer. It can happen even if you're using the standard CD installation, but it seems to appear infrequently. If you're overly worried about that just do what i did and create a full system backup before installing the steam client for the first time. That way you can go back and try again if something goes wrong. However you're far more likely to have an issue with your antivirus conflicting with playonline than it installing wrong. Most antiviruses have flagged playonline as a virus for years now, and the install path is different on the steam version than on the CD version. If you're going to use the steam version I recommend setting an exclusion so that on access and on demand scanning ignore the FFXI folders to prevent potential conflicts. I use bitdefender internet security 2013 and made a special exclusion just for FFXI because it was crashing the game every time I loaded it even after the install, but once I excluded on access and on demand scanning FFXI has worked perfectly ever since.
The normal path for the CD version of the game is
C\program files (x86)\Playonline\Square Enix\Final FantasyXI
The steam version installs to the following default directory
C\Program Files (x86)\Steam\Steamapps\Common\ffxi\Square Enix\Final Fantasy XI
Final note: I use a 64 bit version of windows. If your version is a 32 bit you'll probably have to replace the Program Files (x86) with just Program Files. Someone correct me if I'm wrong, but I believe the program Files (x86) extension is used for the 64 bit operating system and doesn't apply to the 32 bit version. It's been so long since I've had the 32 bit version I can't even remember if I reversed that or not. Edited, Dec 28th 2012 10:54am by Melphina