It's not a real concern but often times I find I type my password wrong or perhaps it's just an issue with the server, but many times the thing tells me my password is not right. Have you guys experienced similar things on here or is it my imagination?

Your fingers or your imagination.

It's possible that sometimes your fingers type in the password letters in the wrong order, since after all when a password is stared you can't tell what letters are written.

The most common reason however is actually CAPSLOCK, people tend to not notice when it's in use and this can be the difference between a password being correct and failed.

When entering other peoples passwords that you've been given (not here of course, I'm sure it's considered that it shouldn't be allowed for security reasons) another common problem is people using a NUMLOCK'd keypad to insert numbers over the numbers that are located above the Qwerty pad.

Obviously there are yet more potential conflicts, like loading the wrong language for the keyboard, OS or browser, but I think you'd notice if you didn't speak Korean.