Recently I am making use of a windows 7 operating system on to my Acer Aspire, additional hardware specifications of my machine are like 4GB ram and 320 GB hard drive, and with that I am making use of the 1TB external SATA hard drive, this was functioning very well but there is an issue from last week. Actually in that it suddenly from last three or four days the hard drive is not identified by my machine. at any time I tried to attach that one through my machine it first take a number of time to install the hardware and a message will come into view as the hard drive is not a not acknowledged by the machine. I have some of the significant data in to that one. Recommend me somewhat to make as running. Any input will be helpful for me.