In HP 6930p unfortunately flawed

Installation of a 8GB kit (2x4 GB) in an HP EliteBook 6930p was smooth in operation (Windows 7 Professional 64bit) occurred but after a while errors and crashes. The subsequently performed HP memory module test then indicated also Error a module already at the first, the second module of the third pass. Item returned. Too bad, because the modules priced (probably through direct sales by the manufacturer) are perfectly acceptable (DDR2 modules are otherwise unfortunately terribly expensive) (tested 100% compatible) and I because the manufacturer had hoped for better insurance / expected.