You can send the fisheye images to support of easypano, and get some advice from them.
And what is the resolution of the panorama you want to get from 45 images? I think the only problem is the memory if you can get a panorama when pre-stitching.
I am experiencing the same problem receiving an error message "#0001002 Failed to open file. Cannot find the file." when I try to stitch six 70 megabyte TIFF files into a spherical at 16000X8000 resolution. I have a Intel Core 2 Duo CPU and 3 GB of Ram. Any suggestions?