I don't know if you're still reading this, ladyravensnest, but in case you are, have you used characters other than the standard ones: the 26 letters of the English alphabet, the ten digits (0,1,2 ..), the usual English punctuation marks, the plus and equal signs, the usual bits of shorthand ( @ # $ % &), this little star * and this: ~? In other words, what is probably on your keyboard, if you're a native speaker of English? If so, that might be the problem. Those non-standard characters aren't always so well supported, even if they are part of the alphabets for other languages, some of them not at all obscure (eg. French, Spanish and German).
I've run into this problem, myself, after putting the accent over the e in café, on my own homepages. It will look nice for a month, then all of a sudden, my page takes that sudden swerve into Mandarin, or black diamonds start showing up.
Annoying, but sometimes restricting oneself to the use of the older ASCII characters can prove to be necessary, even if it does leave one mangling a few loanwords.