lucy24 - 10:06 pm on Dec 16, 2013 (gmt 0)
Wait, stop, rewind.
What is the actual name of your physical file or directory? Some server setups will adjust capitalization to match available files.
If you're changing the capitalization of the URLs you also need to do one of two things: either rename the physical files, or silently rewrite from new URL to old filename.
Worst-case scenario: your server is either case-insensitive or you've got mod_speling [sic] active. This can lead to duplicate content, where "duplicate" = 2^length-of-filename.
Find out what's going on and report back.