From Device manager (my computer/properties/device manager)
You can force a driver.
It could also be a non standard USB Serial adapter. No IRQs are an odd feature. This site recommends other units for more compatibility.
**broken link removed**
Here's one that should work, it uses the Prolific (PL2303) chipset.
**broken link removed**
I use one from Tiger Direct. Also do you have access to a desktop computer with a rs232 port, these will work. And you must change it to COM1 or COM2 (they have IRQs)