I just installed the Comcast-recommended Western Digital 1TB DVR My Book Expander with my Scientific Atlanta 8300HD cable box. Programs do record, however, when playing them back I get video disruptions (pixels messed up) and audio drop outs perhaps twice or more each minute the playback is running. The DVR works fine if one uses only its internal hard drive for recording (i.e., no WD Expander drive connected) but not when the expansion drive is reconnected. I had this same problem with a different manufactures drive a few months ago when I tried using it but thought it was just a compatibility problem with that brand, thus, I went with the WD drive that Comcast said had been tested and worked. The real time viewing of programs is unaffected (i.e., do not have the disruptions except when replaying a program recorded when the WD drive is attached). Any suggestions for a cure?