What, I'm not good enough?
I already said this, but I'll say it again: this is how you fix your [i]thumbnails[/i]:
1. You need to change the permissions on the cache directory to 777
2. After you do that, I'm predicting (actually, I [i]know[/i]) that you need to increase the memory available to PHP. To do that, look at the link in my post above.
Please listen to me, I'm the lead developer. ;-) The fact that the pictures are working is irrelevant, because they're not processed if they're already small, which yours are. Here's what I'm getting when I visit a thumbnail, so you can see the error: Thumbnail error message.