I am going to make a topic on it, but Meowin posted a link in this thread:
http://forums.ddo.com/showthread.php...ight=error+201 that has a lot of info about it. However, that didn't work for my kid. What I did was this:
Went to the games folder.
Looked for the dndclient.log file and opened it.
At the bottom was a section saying which file it could not load.
From the game directory, I moved, not copied, moved the file to the desktop along with patchcache.bin and relaunched the game.
The patcher redownloaded the missing files and we got into the game; no more 201.
However, I am sure that some of the dat files that may be bad/corrupt may prevent updating. So this is just what worked for us.