Cannot retain 'Stop sharing file' facility
 

I'm running the latest version of Limwire. Since I updated, each time I reboot my computer, I find that the 'Stop Sharing File' facility in the Library has deactivated. Although I stop the file share, next time I reboot, all those files are being shared again. Is it just a bug?

Try this: Delete LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will kill all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.

Are you using a stable release, or a Beta version of LW? If you're using the latest Beta (4.13.12), you could post over here at the Beta forum. You'll have to register there before you can post;)
Bugs and Beta Testing - LimeWire Forums