I would try this:
Download a completely clean server zip for your mod pack. This should contain every file that you need to run the server. Unzip it on to your desktop, then run the install.bat. Once the installer is done, run ServerStart.bat. This should (successfully?) launch a completely new instance of the server on your local machine, with a completely new world. Open your minecraft and make sure you can connect to 127.0.0.1, your local world using the 1.0.3 server.
If you are able to connect to this world, then shut down the local server, go to the location where it was running from (where you unzipped it), and then remove the world folder. Replace it with your 'real' world folder that your friends have been playing on. Again, start up your local server (now using your real world) and try to connect with your minecraft once it finished loading. This should also work.
Once you've verified that both of those steps are working, you can then delete the 4 folders (discussed previously) on your hosted server( Take backups first, if you haven't!), and upload all the files from your local server to your hosted server. Make sure that you don't accidentally delete any custom plugins that you may have loaded (if they are important to you), and make sure you don't delete your backups, if they are stored on your hosted server. My host uses McMyAdmin, and it stores its backups in a folder called BACKUPS in the root level of the MC directory.
One thing you may already know: whenever you go to update your hosted server, you will need to make sure that the server is not running. Second, your hosting service may be looking for minecraft_server.jar to start your server automatically -- if this is the case, you need to rename FTBServer-1.7.10-1272.jar to be minecraft_server.jar. If you don't do this, its possible that your host will attempt to 'fix' your server when you start it by deploying a default minecraft_server.jar, and loading your world with a default server jar will almost definitely cause corruption.
I had a lot of trouble getting all this to work myself, so please let me know if you have any more questions.
Good luck!