I seem to have a similar problem to those recently reported.
Previously this was working great, but now when ever I try to resize (batch or individual) I just get sent to the Regenerate Thumbnails page and nothing happens,and page displays something like:
Total Images: 239
Images Resized: 0
Resize Failures: 0
It just won't seem to run the script. Weird, as was working fine earlier.
One thing to note is that I have cleaned out all but the original images from my media library - and now want to build all the other sizes as per WP Media settings.
Is this a bug?