In this paper we analyze the effects of interchannel interference (ICI) and intersymbol interference (ISI) on the performance of a Multi-Symbol Encapsulated Orthogonal Frequency Division Multiplexing (MSE-OFDM) system. MSE-OFDM is a bandwidth efficient OFDM scheme, where a number of OFDM symbols are grouped together as a frame and protected by one single cyclic prefix. This reduces the extent of redundancy caused by the CP and increases the bandwidth efficiency of the system. We have derived expressions for probability of error for MSE-OFDM in presence of ICI and ISI, which result from the time variation and delay spread of mobile channels. Both analysis and simulation results are presented for the MSE-OFDM system and are found to be almost identical.