[makkonen]

Hmm. I didn't think running unsigned applications was an issue... I know I haven't had to deal with it in a long, long time. But it might be worth searching to see how to make sure unsigned applications will run correctly.

But I'd guess it's more likely that the file's just corrupted or something. I'd try redownloading the package and reformatting the SD card. (I feel like a quack doctor -- any problem, I give the same cure. Take two of these, reformat, and call me in the morning.)