I've noticed something wacky with thumbs, I always upload a Thumb with mine never Autogenerate one and always 300x200 in sixe but the last few uploads I've needed to go back and change the thumbnail again later. It's easy to see when it happens because it skews the layout, the 300x200 thumb is now 300x169 I would change it in Edit and it would be ok but now the edit doesn't seem to work. It really blows the uniformity of the page layout, what's up.

Remember...No matter where you go there you are