I receive cannot defrag read only volume. ?what now?

When I try to defragment my hard drive C, I keep receiving the message,
cannot degfrag a read only volume. I don't know how my C drive became read
only and I don't know how to undo the read only status. Can anyone help me
with this problem?

click on 'My Computer', right-click (C drive, select 'Properties' ,
select the 'Security' tab from the 'Properties' dialog, select your name,
'Allow' yourself 'Full Control' of this drive

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Mark L. Ferguson
..

"rlw@sb*" <rlwsb@discussions.microsoft.com> wrote in message
news:FD986F09-75FE-4C59-BF2C-B2E100ECD1FD@microsoft.com...
> When I try to defragment my hard drive C, I keep receiving the message,
> cannot degfrag a read only volume. I don't know how my C drive became
> read
> only and I don't know how to undo the read only status. Can anyone help me
> with this problem?