Have you tried a complete fresh install of the launcher and modpacks?
To do this, download a new copy of the launcher and put it in a new folder like c:/ftb/client.
Before running it, navigate to your appdata/roaming folder and delete the ftblauncher folder.
Now run the new client.
You will have to manually copy an worlds you want to keep to the new modpacks created.
To do this, download a new copy of the launcher and put it in a new folder like c:/ftb/client.
Before running it, navigate to your appdata/roaming folder and delete the ftblauncher folder.
Now run the new client.
You will have to manually copy an worlds you want to keep to the new modpacks created.