A WD25EZRX hard-drive (2.5TB) fails after few days of functioning, isn't even visible anymore. When I disconnect it for some time and reconnect it, it functions again a day or two and then stops functioning again. This disk is a replacement of another disk, which had the same symptoms. So problem is not disk itself, I think, but system.
Dell Inspiron 530
OS Version: Microsoft Windows 7 Ultimate, Service Pack 1, 32 bit
Processor: Intel(R) Core(TM)2 Duo CPU E7400 @ 2.80GHz, x64 Family 6 Model 23 Stepping 10
Processor Count: 2
RAM: 3317 Mb
Graphics Card: Intel(R) G33/G31 Express Chipset Family, 256 Mb
Hard Drives: C: Total - 294940 MB, Free - 185705 MB; D: Total - 10239 MB, Free - 4679 MB; O: Total - 953197 MB, Free - 157661 MB;
Motherboard: Dell Inc., 0K216C
Antivirus: avast! Antivirus, Updated and Enabled