The purpose of this study is to examine the efficacy and safety of venlafaxine XR in the treatment of physical and emotional symptoms in patients with an operationally-defined diagnosis of MSD. Primary efficacy will be evaluated using the PHQ-15 scale, and secondary efficacy will be evaluated using the HAM-D17, HAM-A, CGI, MQOL-PS, VAS and SF-36 evaluation scales. Assessment scales and questionnaires will be administered at specified clinical visits between screening and Week 12 (or discontinuation).