I used to scan a thumbnail sized pic directly 
from my scanner, but found it to be difficult to 
get them all the right size without cutting off 
some of the image, or going outside the original 
image....So...

Now I just make a large scan, & then use that 
large scan to make the thumbnail.  I crop it, & 
re-size it in Paint Shop Pro 7.  All my images 
seem to load fine for everybody.

Hope this helps =)