Tony,
I would do the following:
1) remove the iplayer
software via Add / Remove programs. Unless you use it, you may also need to remove QuickTime. Also check that other Apple crap like Bonjour is not left behind. Disable the service, if so.
2) check to see if your file associations have been restored as they were previously.
3) if not, open VLC and see if there is a configuration option to "restore defaults" relevant to the file associations. If not, then remove VLC and reinstall it, which should then allow you to select the associations or accept the defaults. Possibly just re-installing it may do the same job.
4) If there are any remaining associations that you want for Media player, set those manually.
SD