Why can't I remove this file?
root@testserv [~]# rm /usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe
rm: remove regular file `/usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe'? y
rm: cannot remove `/usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe': Operation not permitted

Details:
root@testserv [~]# lsattr /usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe
s----a------- /usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe
root@testserv [~]# mv /usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe /root/
mv: cannot move `/usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe' to `/root/fpexe': Operation not permitted
root@testserv [~]# chattr -i /usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe
root@testserv [~]# mv /usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe /root/
mv: cannot move `/usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe' to `/root/fpexe': Operation not permitted
root@testserv [~]# ll /usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe
-rwsr-xr-x 1 root bin 7660 Dec 5 15:21 /usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe*
root@testserv [~]# rm /usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe
rm: remove regular file `/usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe'? y
rm: cannot remove `/usr/local/frontpage/version5.0/apache-fp/_vti_bin/fpexe': Operation not permitted

You have the answer in the file attributes. The attribute 'a' means the file can only be open in append mode for writing. You cannot delete nor empty it. If you really want to delete it, just remove the attribute 'a':