Really stumped with this. I built a Win 7 PC, and reused a couple of SATA HDD's from the old XP machine.

Many files then disappeared from the HDD's, as if the Win 7 machine coudn't see them. Various freeware file recovery programs found nothing either.

I put the HDD's back in the XP machine, but the files could not be found there.

Now the HDD's are back in the Win 7 PC, but I now find that one HDD has now lost its volume name and the partitions on it (split into 3) have disappeared. It now presents itself a big drive with 830Gb free. Documents created on the new Win 7 machine and stored on this HDD have now disappeared.

It is worrying and driving me mad. Is it Win 7 being funny ? Have I put the SATA cable in a different connector on the motherboard - indeed does it matter ?

I am the only user on the PC, with administrator rights, and its Win 7 32 bit.

Welcome to the forums.

What's the other hardware in the machine?
Is it overclocked?

It sounds like you've got a dodgy HDD (or two) but could be a failing controller on the board.
How old were the drives?

Thank you !

PC is intel i7 860 with MSI P55-GD65 Motherboard, built in January, not overclocked.

The disks were only 14 months old, and perform without problems apart from this.

There are three HDDs in the machine - a new SATA 80Gb for the C drive, and the "old" ones are for storage - a large SATA and a smaller IDE one. They did have documents, MP3, images on them.......migrated from the XP machine.

When I put the Win 7 PC back together, it did notice a hardware change and Win 7 wanted a restart. I presume this was due to a different SATA port on the motherboard, but why should it make a difference ?

Otherwise, no funny noises, odd behaviour or error messages.

Is the port you moved it to set to IDE compatable, native or ACHI (or something like that)?
Are all the other ports set the same?

I'd probably start by changing the sata cables just to be sure.

What PSU are you using?

PSu is the stock 500W one that came with the cheapo case.

Have to power off to check details..........

Dump the cheap psu and get a proper one (£40 minimum)

I bet you've got an iffy rail that's undervolting (or overvolting) the HDD and freaking out the controller.