The average bit error rate (BER) performance of interference-limited dual-hop decode-and-forward (DF) cooperative systems with cochannel interference (CCI) at both relay (R) and destination (D) nodes is analyzed in Nakagami-m fading channels with arbitrary (integer as well as non-integer) values of m. This channel condition is assumed for both the desired signal as well as cochannel interfering signals. In addition, the practical case of unequal average fading powers between the two hops is assumed in this analysis. Accurate closed-form approximate expressions for the BER performance of binary phase shift keying (BPSK) modulation scheme are derived. The analysis assumes an arbitrary number of independent and non-identically distributed (i.n.i.d.) interfering signals at both R and D nodes. The derived closed-form expressions are simple and easy to evaluate. We verify the accuracy of the derived expressions using Monte-Carlo Simulation.