I've been using a My Book 500GB hard drive as a slave drive for a while now but today it suddenly wasn't appearing. For a while it would appear on My Computer every few minutes then quickly disappear after it went through the files for a few seconds so I tried plugging in the USB from the back of my computer and it got stuck on the first file and I could view the files but not use them. After restarting it's not appearing at all anymore. What do I do?

Hi - maybe a removable drive power supply issue - as it heats with use up it fails , so I suggest first check that the hdd is still spinning when drive stops being detected by windows.

If the drive is still spinning then possibly a usb sub-system driver error related issue or windows system file related issue

or possibly a drive firmware issue , so just 1st check the vendor support site, install if possible any recommended firmware updates
(firmware is device located, device driver software)

run HD Tune > disk error scan to ensure no bad sectors on the disk that may have unluckily been located at the usb related driver locations

as a precaution run check disk windows disk structure repair utility
start run > enter : chkdsk /f /r
enter Y in popup
restart system

anyhow if not a system disk drive integrity issue and if not a known device issue

I suggest isolate windows vs device by running a ubuntu linux live install disk with BIOS setup configured for 1st boot = optical drive ie cd-drive
This os will load onto the ram memory only, and without altering any hdd data - in fact will not detect the onboard windows drive but will detect any installed removable drives (or should)
have the removable storage device plugged in and a flash drive to confirm linux install is working correctly (flash drives will definately be detacted)

these freeware os's can be download as an iso file for free or a disk ordered for about $10 i think

now if the removable drive works ok and is stable , then a windows system or usb driver issue, if not, then most likely a drive hardware, firmware or ps issue

now if works ok - it is back to basics for the installed windows system by
upgrading the pc BIOS driver from the vendor support site, so as to add updated usb support if applicable and /or overwrite errors

(read instructions carefully, know the fail-safe procedure, run a backup if prompted, do not upgrade during a thunderstorm,
reformat the install diskette as a precaution, if used, if in doubt don't)

upgrade the chipset or mainboard installation driver if possible

upgrade any usb related drivers if applicable
also check the usb or chipset vendor site for later release upgrades

if using a retro-age system with only USB1.1 support , then install a good pci USB2.0 expansion card and upgrade the driver
USB2.0 drivers are more compatible with modern usb devices - so less problematic

If stiil a software related problem then I suggest save all c-drive personal files and install trialware Windows 7 RC
this will at least remove any parasites and any current os system errors