Have you tried making apache the owner of the file in question?
Otherwise, it can never actually do certain file operations in a directory which has the sitcky bit set (the last t in the mode)
Update: Also I would change the mode to something a bit less dangerous.
#WARNING: non perl code follows! chown apache /tmp/FileCache chmod 700 /tmp/FileCache #End of non perl code
More update: corrected file mode as noticed by sgifford that the FileCache is a directory not a file
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