The deleting 100 at a time process worked for me. I had to delete about 70 pages of 100 images, AuctivaJeff, and it took me far more than an hour because there's a wait for Auctiva to list the 100 images. But my 2 gigs got down to under .5 gig.
The problem is that I had ALREADY deleted these images, according to Auctiva. I keep my one-time post images on eBay for around six weeks, as a research service to my customers (I sell philatelic covers and the customers like to see the sold items for a while). Trying to be a good Auctiva citizen, even when it was free to hold images, I've stored only a max of 2 months of images, and delete the third month file just to save Auctiva storage space for images my customers don't care about. Have done that for years on Auctiva.
But Surprise! I find that over nine months of images I deleted were not really deleted, until I did them manually 100 at a time. Auctiva really needs to get their Deletion Wizard act together.