If I double-click on the SC exe file on the desktop of my existing machine, it runs correctly - you can see it in the systray in the image below:

Now, remember that this is the very same file that I've been emailing to people and they've used it successfully. However, when I now use a USB flash drive to transfer the file over to my new machine, this is what I get when I try to run it:

I've also tried transferring the file on floppy and CD in case the flash drive was the problem and I've also tried transferring it to my laptop using all the different methods but still with the same result.
Why does it work on my existing machine but now - after 7 months of successful use and being emailed far and wide - does it come up with this dialog box?
Cheers,
John.