So reading the Astro Tortilla forums -
https://sourceforge.net/p/astrotorti...read/b5546e48/ - this may be an issue introduced in the last version of code. One other person has reported Centering working in v0.51 but broken in v0.52 - may try the earlier version when the clouds clear!
BTW
Tried M83 - a 600 second shot on x86 version v0.51 on a dual core Conroe2 2.3GHz machine, Windows 7 sp1 machine with 8GB RAM and a SSD - found 100 objects - took 26 seconds to solve - yah!