A Gilbert-Elliott channel for symbol errors is considered to analyze the performance of interleaved error correction codes with a fixed block size in the presence of burst errors. The proposed channel model for symbol errors is based on a simplified Gilbert channel for bit errors, which enables direct comparisons of the performance of block codes with different symbol sizes. The autocorrelation function between two erroneous symbols within an interleaved codeword is computed. An exact expression for the codeword-error probability is derived from the symbol-based channel model. A tight lower bound on the codeword-error probability and error floors, which are observed when the average raw bit-error rate is low, are analyzed using the bit-based channel model.