I don't know if this applies to your situation, but I own a picoalt altimeter that comes with windows software and a serial port cable so I can program it .....
anyway, the software will install fine on both of the 2 pc's that I own......these are P3 1Ghz and Cel 1Ghz cpu....intel 815E chipsets....perhaps 2 years old at best........ the software could not see the altimeter on either pc....1 pc runs win2kprosp4 while the other pc runs a dual boot of win2kprosp4 and winxpprosp1
so I went next door to a person that has a cheap E-machine running win98 and installed the software and I was then able to program the altimer......
I then installed the software on a friends compaq notebook (rather old 300Mhz cpu) running win2kprosp4 and it communicated fine with the altimeter...
So I then called the maker of my altimeter and was informed that certain serial port UARTS will not work with this cable and software, that I needed a "smart" cable.... perhaps something similar here is the problem?
as far as com ports go, you of course usually have 2 serial ports per pc... they usually have to be enabled in the system bios.....I usually disable both of my serialo ports as I have no serial devices....this allows for me to use the IRQ 3/4 which the serial/com ports usually use. So go into your system bios at bootup(usually press Del Key) and see if you even have com2 enabled...
Standard COM Port Settings
Port I/O Address IRQ
COM1 3F8h 4
COM2 2F8h 3
COM3 3E8h 4
COM4 2E8h 3
as you can see com1 and 3 share irq 4 while com2/4 share 3...perhaps your device driver doesn't share properly.....
heres a place that has some usb/serial port adapters which may help...
good luck
https://www.usbstuff.com/serial.html