Error message after changing a word in lang " "

I changed a few words in the lang files (only between the " " so not in the codes themselves) i.e. from "email" to "what is your email address?" And got the following message;
Warning: Cannot modify header information - headers already sent by (output started at /home/alan/public_html/guestbook/lang/english.php:105) in /home/alan/public_html/guestbook/lib/admin.class.php on line 36

I've counted to line 105 in /lang/english.php I can't find anything wrong and didn't modify anything apart from having changed the words.

Any ideas?
By the way - is a full line of script one complete line even if it shows over two or three lines (cos of window restrictions) or is a line counted as each time a new line starts? Does that make sense?
Ta