The driver was not installed properly. The user is to blame. Buying a cheap adapter is the fault of the user. Finally, actual data can be lost because of the USB Host Controller that resides on the PCI Bus within the motherboard itself. This is mainly the fault of the advent of USB as there was a discussion a long while back where USB requires a "HUGE" FIFO. What happens is that if the user's program does not "sit" on the USB Host controller's buffer the host controller will over write it's own buffer causing records of data to be lost as the host controller does not have infinite space. So, if the user's program does not poll the serial port fast enough, data is lost. One can account for it by having a large hardware FIFO and increasing the "latency" so that the USB Host controller does not have to continuously service the FTDI chip. There is another method, but one cannot easily perform it with the use of an FTDI chip. In essence, these converters are a generality of a serial port and cannot be made to consistently give correctness for a given application. If someone were to use these converters blindly, do not expect your design to work perfectly. As pointed out before, just because it works, doesn't mean that it is correct.