Have you used this combo of decoder, computer and software successfully previously?

Have you used this decoder with another computer/software successfully before this?

The decoder has 3 protolcols; Remote, Enhanced and P3. I think Remote is default, try P3.

Are you using the ethernet cable that came with the decoder directly to the computer? The black cable with red connectors that comes with the decoder is a crossover cable not a standard cable.

I assume from your post your computer and operating system is 32bit. If your system is 64bit and the Sparc software is 32bit, is the software installed in the "Program Files (x86)"?

Have you tried to update the LAN drivers on your machine?

Can you try installing on another computer?

Last resort is maybe downloading a trial version race management program that allows the use of the ethernet cable, like JLap?