Windows 7 - USB HDD problem

Hello all
Recently I upgraded my computer from windows XP SP3 to 7. I have 3 external USB drives formatted with FTFS, one is 200G, second 250G and third 500G. All drives are fully accessible under XP, in Win 7 500G is not accessible.
When I connect 500G drive in Win 7 I am gating message:
H:\ is not accessible
The file or directory is corrupted and unreadable
Under Disk Management drive H: shows as RAW, 100% free.
Is there any way to fix this problem other than formatting this drive. I have about 400G of backups and data on that drive.
Please help
Thank You

See if an Ubuntu Live CD can read the data, then reformat the drivers. What file system is that?

Hi maxx102,

A few thoughts:
1. Are your USB ports working correctly? i.e. does a little old usb stick work fine?
2. Download the chipset driver from the manufacturers website. e.g. go to Intel - put in your CPU name and download all drivers. This fixed the same issue for me on a clients PC last week.
3. Try different USB ports, preferably those in the back and directly on the motherboard. Try this with no other usb devices attached (i.e. do it one at a time) and reboot with the usb device plugged in. If you get it to read then open an elevated command prompt and run a CHKDSK [volume[[path]filename]]] /X /R (e.g. CHKDSK D: /X /R). De-fragment the drive when complete, or even better get your data off it and reformat it, then put your data back on, this ensures that the partition tables are correct.
4. Check the wattage on your power supply to ensure that it is easily capable of running your system. There are many power supply wattage calculators on line.
5. Ensure that your motherboard is configured to run large drive sizes (not sure if you upgraded this or touched it between your upgrade, but just want to cover it).
6. On my netbook (which is XP but read on anyway), I need to power up one of my usb drives and wait about 10 seconds before I plug in it into the usb port. I've been too lazy to fix this, as the work around always works for me. If this works then run the CHKDSK as shown above and then de-fragment the drive or rebuild it as I instructed above.

Good luck!

This is also good advice.