No ERISA Event has occurred or is reasonably expected to occur that, when taken together with all other such ERISA Events for which liability is reasonably expected to occur, could reasonably be expected to result in a Material Adverse Effect; provided , however , that the occurrence or reasonable expectation of the occurrence of any ERISA Event that could reasonably be expected to result in the imposition of a lien by the PBGC on the assets of any SPE shall be considered as reasonably expected to result in a Material Adverse Effect.