[Sirathiel]

Yeah, I too am gifted with a name people tend to misspell more often than not. As to why Tolkien's name is mispelled so often... Maybe it's because it's two vowels?
On another forum I frequent there's somebody with the nick of Tuecer and the poor person is spelled half the time Teucer. So, my guess is, it's a vowel thing.

~Sira.