Disk is Write Protected

Running Vista64 Home Premium SP1

About every 4 or 5 times I boot the system, my data HDD D:\ presents as
"write protected". A reboot corrects this. I have run diagnostics on the
HDD and all appears OK.

Any ideas how to solve this problem?

Your D: drive is where the factory installed your installation system, like
having a DVD installation disk, built in.
You should not install any programs there.
If you need another partition, shrink C: drive and create a new partition in
the Unallocated space.

No, D:\ is a separate physical hard disk that I added. I assembled the
whole PC myself. It is nothing to do with a "restore" partition.

Thanks for trying to help.

You might go to cmd.exe,
Right click and select Run as Administrator,
Then type ATTRIB -s -h -r D:*.*/so
to remove the attributes.

I have admin rights and I did select "run as administrator", but I was told
"access denied". It's a strange problem, usually cured by a reboot.

If you want to monkey with that, boot from the Repair Disk. This is a
stand-alone system that can modify things without your normal system getting
in the way.

Just wanted to say i have the exact same problem as The old bloke. Seemingly
randomly my data disk get write protected after boot, never had system on it
but i reinstalled Vista-64 SP1 a while ago on computer.

Have: Gigabyte GA-EP35-DS3R, 2x150Gb Raptor in raid0 as system disk,
1xCaviar 320Gb as Datadisk, Vista-64 SP1

I believe this message is appearing if one has an encrypted disk - like
truecrypt. Very frustrating. XP did not have this problem. Looks like
another VISTA bug.

Most of the so-called bugs these days are of the PEBKAC variety.

after 2h research no solution came up that worked for me on a similar problem:
a usb external hard disk drive suddenly got write-protected in vista.

fs was exFAT

no solution worked: neither modding the regex nor uninstalling usb drivers and re-plugging after reboot (as ms kb suggested) nor fiddling with command line diskpart tool.

maybe a hint for all, who stumble upon this via search engine:
i connected the drive to a windows 7 (64-bit) laptop and a popup asked me if i wanted to check filesystem in order to avoid problems. i did successfully and windows 7 accepted the drive without any further problems.
then i re-connected to windows vista and voila - it worked again.

so maybe - whatever the root cause was - the disk became marked dirty.
after this i would add "checking for inconsistencies of the filesystem" to the list of what-you-should-try.

i am sorry that i know cannot test again if that really solved it and if that would work anyway - depending on the level where the lock is applied.

enjoy