Same source HDD (Maxtor 80GB, only one FAT32 partition with WIN98 SE), same data (13.7 GB, not 1 bit less, not 1 bit more), same compression level (normal), same target drive (Iomega USB 2.0 - 160 GB). Two DIFFERENT results: Backup # 1 with TI8 (using its rescue disc)=> 3 images, for a total size of 10.2 GB. Backup # 2 with TI9 build 2259 (using its rescue disc), made just a few minutes after backup # 1 ended => 2 images, for a total size of 7.52 GB. And, although I got the usual frustrating error ("completed with errors") in the second case, the images created by TI9 successfully passed the verification. Can someone explain why the size of the former backup is considerably bigger than the size of the latter, considering that NO data has been added or removed from the source between the two attempts, and the compression level has remained UNCHANGED? I must precise that something like this already happened to me once or twice in the past, when TI9 had not been released yet, and I was still using TI8. In a couple of cases, in fact, TI8 produced two backups which were considerably different in size, even if such backups had been made just a few minutes apart, and no data had been added to/deleted from the source in the meanwhile. Thank you in advance. PS I forgot to say: I am talking about FULL backups, not incremental.