I've been using Defraggler for a wile on my windows xp pro (32bits) but now I've switched to vista x64 (and 1TB disks) defraggler crashes so often... often i can analyse but after that it halts and doesn't respond any more... sometimes I can defrag but when it is finished i can't review the results because it halts... i would like to stay using defraggler but if it stays like this i am not going to... i hope piriform increases the performance of her program on vista 64 bases systems with large disks...