You know that's just odd. I've installed LCDPFR numerous times with no problems. I did a fresh install of GTA IV a day or two ago, and now all of a sudden I get that error too. And I did like you said about not linking my account and it worked. Wtf?
And if anyone asks to make sure I did like Break did in the video, yes, I even did that. The thing is, I never had to do it like that before, and even then, it didn't work. Every time I unchecked read-only in my GTA IV folder, it would do just that. Then when I checked it again seconds later, read-only was checked again.