Transferred hosts, now images not working?

I transferred my website from one web host to another (Hostmonster.com to GreenGeeks.com). GreenGeeks did the transfer.

Now, my problem is that random images aren’t showing up, but only at random times!

For example: The thumbnail images for each post on my blog page are randomly not loading. I’ll hit refresh, and the ones that were missing will load, but others don’t.

The same goes for my portfolio pages and on my home page.

Even when the thumbs don’t work, I can still access the link and see the image. Could the thumbnail generator on my theme be messing up?

Links:
http://www.ironsidephotography.com/
http://www.ironsidephotography.com/category/blog
http://www.ironsidephotography.com/category/portfolio

Any ideas? This wasn’t happening before the transfer…