So, i have an CI+ TV, and i changed mainmenu.swf in /mtd_tlib/swf/ without any problems.
/mtd_contents <-- this one "has to" be empty, its the TV`s database for thumbnails etc. from your USB, SMB etc. files, i had allready delete the hole content in it without problems.
i don`t know if 40 sec. are enough, BUT if you are able to delete content from library, you should try to get in this menue and delete it.
If your changed files in WILDLIFE are the problem, i really doubt it, then this should help you out.
Are you sure you haven`t changed touched or even looked inside another file?
Have you edited any files with windows editor or wordpad and transfered it back?
Once i downloaded almost whole content from my TV with help of this FTP, ftp is also starting everytime my TV powers on.
Had no bad experience with it.