Well, I noticed the FAQ was recently posted but It didn't cover the other solution for the Crash @ Login bug. Now, This bug is quite random. I have the .NET Framework 3.5 and I still experience this bug sometimes. Some people think installing the .NET Framework helps, But it really doesn't since the bug is random (sometimes you can login, sometimes you can't).
What to look for: Once you get to the login screen, Move your cursor around. If you notice the cursor is lagging then the client will crash when you login.
How to Fix: Simply press Alt+Tab to minimize the client. Then, Press Alt+Tab once more to bring the client up again. And there you go! All better, You should notice that the cursor doesn't lag anymore and you will be able to login without any issue/crash.
