There are some glitches where, let's say, your username is bubblegum. When you type "bubblegum" to log in, you log in, but your name gets changed to "Bubblegum" (even if it's still lowercase for you, it appears that way to others) So if you log in with lowercase letters, try using a capital. (Or the other way around, if you use a capital, try a lowercase.)
Also,
The .fhp is case sensitive. If you log in as 'PAiNFul' and your .fhp is 'Painful' then it won't work.