jwplayer.js file is being deleted

For the last 2 weeks I have been having an issue with the jwplayer. On my sermon page I get a message that says "Player needs JavaScript turned on" in place of the actual player. I eventually figured out that the message was a result of a missing file jwplayer.js located in .../media/com_sermonspeaker/player/jwplayer/. As soon as I replace that file and refresh my page the player works great. My issue is the file is being removed every night. I've been working with my hosting provider and they have assured me that they are not running anything that would remove files from my system. Their recommendation was that Joomla is most likely removing the file. I have not found anything that supports that theory. I have attempted to lock down permissions to that folder and file so it is read only. I'm not having any other issues with my site, so it seems that this is the only file that is mysteriously disappearing.
Do you have any suggestions or ideas that may lead me to figure out what is happening with this file?

www.mcachurch.org/mcamedia/podcast
SermonSpeaker version 4.5
Joomla version 2.5.14

I have finally uncovered the issue with the file being removed, so I thought I would post the resolution. I have been searching for this problem for weeks, each day I would upload the jwplayer.js file so our sermon recordings could be played. I did file by file comparisons with the last known good version of my site. I finally gave up and asked my host provider if they could help me through log files or some type of trace that could pinpoint the process that was removing the file. As part of that process the hosting provider realized that their malware software was removing the file. Thankfully I had not been hacked. Regretfully, I have wasted many hours trying to find this needle in a haystack that they could have resolved the first time I asked.

Thanks Thomas for your reply and advice. It is always appreciated.