I had this problem since updating to 1.0.72, then I fixed it by copying the two .lsx files from another computer, but now the problem is back on the latest patch (1.0.78) and the workaround I had before doesn't work anymore.
The error message doesn't exactly say mod Main, but rather: "The files of mod '' and/or its dependencies ..."
Does anyone have any working workarounds for this? Is there a way to downgrade to the version before 1.0.72 so we can continue playing? (Installed on Steam)