All these .sav files run under spider.exe supplied with Windows XP, and apparently that program runs under later versions of Windows if you copy the exe file across.
- Download a doable Spider saved game from this website.
- Save this file to your "My Documents" folder (be sure this is named as spider.sav).
- Start the Spider application and select Game > Open Last Saved Game. This will show the last saved position of the game you have downloaded - evidently solved!
- Select Game > Restart This Game.
Happy Spidering!