Hi Richincome,
You'll need the latest install archive from the sounds of things, 4.1.9 included security changes to x-cart which feed manager was upgraded to take into account.
I'm assuming you're running on a version of feedmanager which was developed before 4.1.9 was available.
If your support is still active you can log into the firetanksoftware.com members area to download, if it's expired you can renew support directly via the upgrades area.
http://www.firetanksoftware.com/