I option+restored to 3.0.1 (from 3.0.1...just have a bug displaying my photo library), but got the message: "Your iPhone is not eligible for the requested build."

I tried downloading 3.0.1 from two other sources, and now I'm getting this error message: "...could not be restored because the firmware file is not compatible."

The only reason I haven't just done a complete restore is because I don't want to lose tethering by "automatically upgrading" to 3.1.

Thanks in advance for any help.