There is an installer for the COMM driver in the Misc folder on the CD. I really don't know if the stock COMM driver in XP has that same old problem or not.
There is also a well known bug in some of the UART chips in various motherboards, they don't set the bits right for hardware handshaking. At one time virtually half of all the IBM laptops had this problem, according to their own service notes. The same defective UART chipsets were used in many other brands as well. So that kind of a hardware problem can also produce failures in RS-232 communications.
Best thing you can do is try a different COM port. You can get USB-COM adapters also to create more COM ports for $10. Sometimes you have to change their default driver settings as well, because some have so much latency they don't respond fast enough to work right. But generally they can all be made to work.