I tried booting in safe mode, but the problem persists. I still get stucked when logging at "preparing yor desktop". After a while, I get an empty screen (it loggs but nothing is loaded, so i can't do anything).
I noticed that i also got in the corner of the screen a warning telling me that "this is an illegitimate copy of Windows". Is there any chance Windows has an anti-cloning system which prevents me from logging? Anyway, I can't introduce my key, due to Windows not logging my session.
I haven't erased the old Disk, so re-cloning is still an option, if you think this issue could be due to some problem happening during the process of cloning (although according to Acronis, it was succesful).
BTW, thanks for your help, I really appreciate it.