I have 2 HDD in total (1 SATA and 1 PATA). I have Windows XP on SATA HDD. But during installtion, the boot loader was installed on primary partition of PATA HDD. So the Windows XP drive letter was D:. So I tried to change the drive letter to C: using Acronis Disk Director. After that I am unable to boot XP properly. The boot process stops before where it asks for username and password. So now I am not able to use the computer. Can anybody tell me why this happened? Any help will be very helpful.