USB to Serial Disappears from Windows 7 Device Manager when Tx of board connects to Rx of usb-to-serial converter
Arduino and Raspberry Pi serial ports are, as far as I know, "TTL" level serial (3.3V or 5V) and it sounds like the USB-serial cable is design for this.

Since you are connecting your work device (does it use a DB9 or DB25 connector?) directly to a PC's PCI card, I'm going to assume it uses RS232 signalling. RS232 is a different voltage level and the signals are inverted vs. "TTL" signalling.

You probably need a USB-RS232 cable.