The apparent necessity of a "cheater plug" in any system indicates that one or more of the components employee an ineffective grounding scheme. The earlier posts that raise the concern of safety are very valid points. When a component has its third wire (mains ground) disconnected, then only connection to the safety ground is via the connections made to other components, typically this would be through the shield of the interconnects. While the interconnect may be capable of carrying the fault current, the internal path is unlikely to have the capacity to sustain the fault. What could result is that the internal ground path might open, this would leave the product with the cheater plug unprotected (now a shock hazard) and could have damaged the product(s) to which it is connected. Rather than try to apply an ill-advised fix (a cheater plug) try to isolate the actual cause of the problem. You might find that the manufacturer of one component has failed to follow good grounding practices or perhaps you have an external leakage current path (cable TV connection, etc). Play it safe and don't do things that might result in a hazardous condition. Kevin Halverson