Yes, they can. Some users have good success with the FIFO buffers Enabled. Others have good success with the FIFO buffers Disabled.
So, the best advice ProSoft can offer is that, if you are trying to get serial communication with one of our solutions and your efforts are not successful, check the Windows COM port settings and look for the FIFO buffer check box. If it's checked, uncheck it. If it's not checked, check it. If neither of those options allow you establish communications, try a different PC, preferrably one with a regular 9-pin serial port (not just a USB-to-Serial adapter.)