Thanks to everyone who helped! Even if Nexon figured on their own you guys managed to find the temporary fix described below. You all are awesome.
END OF IMPORTANT NOTICE
IMPORTANT LAST MINUTE INFORMATION: A POSSIBLE BYPASS HAS BEEN FOUND, TO AVOID THE ERROR CODE.
To bypass the Error Code 38, you must have a resolution different than what it would switch to when accessing the servers of the content you are locked down to. For example, set a resolution other than 800x600 on a different character if you have a phase 3 lockdown, and then insert you PIN while on windowed mode. Just before the screen fades to black, click and hold the window top border until the resolution changes. If successful, you'll log on the character, and the resolution will look funny. You can now select any resolution from the menu, but you'll have trouble selecting it with the cursor, so use the keyboard.
So far, I only managed to have this work with phase 3, not monster life or the cash shop.
Thank Asylum for finding this out.
EDIT: I have tested this a bit more, and upon getting this method to work, it is possible that cash shop items expired on me as I tested this, so further tests are required. If it's attempted at phase 3, it's likely that the crash will still happen when the screen fully goes to black.
And now we continue with the rest of the data gathered.
Basically, this error locks a character in your account, so that when entering your PIN, the client crashes with a "error code 38" message.
I'd like for everyone affected to contribute here, to add new things, or confirm suspicions. These are the weird things coming with it, that I'm aware of so far:
The bug includes 3 CONFIRMED phases. It's most likely possible that everyone could be eventually affected. The phases are:
-Phase 1: Monster life lockdown. Error Code 38 appears when entering Monster life only on said character.
-Phase 2: Cash Shop lockdown. Error Code 38 now triggers when entering the Cash Shop.
-Phase 3-a: Character lockdown. Error Code 38 now triggers when entering the PIN code on the affected character. However, lockdown can still be averted by removing link skills. Possible bypass seen above, if triggered when enough items have expired from your inventory so your limit isn't bypassed.
-Phase 3-b: Full character lockdown. Error Code 38 still triggers when entering the PIN code. However, the removal of the link skills no longer reverts past the limit needed, so the character can't be accessed anymore.
-Guild and buddy notifications ('character has logged in') do manage to pop up when you attempt logins for other people. CONFIRMED
-Characters affected by it, also got affected by error code 38 when accesing monster life from that character. CONFIRMED
-Character affected is usually played often and/or main character. CONFIRMED
-Shortly before having the character locked down, error code 38 would trigger when entering the cash shop. CONFIRMED
-Last action before lockdown (temporal and permanent, see below) was changing channels CONFIRMED
-Character has expanded inventories. CONFIRMED
-Items seem to be the cause. Having items past a certain point trigger the Monster life lockdown, further into it, Cash shop lockdown, and further into the limit, full lockdown, link skills seem to add towards the limit, so exceeding the limit and then removing link skills can also result in lockdown removal temporarilly, as long as the limit is kept. CONFIRMED
-Character suffered from Error 38 on entering cash shop bug 3 years ago (http://www.southperry.net/showthread.php?t=34911)?. (TO CONFIRM)
-Character was created and used from before the shut down of the MTS. (SPECULATION)
-Affected accounts are from a foreign region (outside North America and Oceania), created before the "new account area restriction". DEBUNKED
-The locked down character is available to relog back for a variable ammount of time (estimated around 2 hours) ONE time, before becoming finally 100% locked down. DEBUNKED
IGNs and world doesn't seem to have a relation so far, unless new worlds don't suffer from it. That could set characters created before some point.
Any kind of possible insignificant info can help. And as far as I'm concerned, the first "fix" before the final lockdown is automatic somehow. If you think you have a fix, make sure you don't get locked down again after it.