Why won't windows 7 setup let me format my drive?

I currently have Windows 7 installed on drive C: I was doing things that I shouldn't and the OS became unusable. I want to format the drive and reinstall windows. I don't want to create a Windows.old folder, I want a clean formatted drive with a new installation of windows 7.
From the install CD I click on "customize" and then when prompted where to install Windows I click on "drive options" but from there, it will not let me remove, delete, or format any of my partitions as they are all grayed out. Why won't Windows 7 install let me format the drive for a clean install?
There's 4 partitions listed??
1. o data, unallocated
2. 100mb system reserved
3. 698gb primary HDD?
4. 0 data unallocated

Disk - Clean and Clean All with Diskpart Command

mborner said:

I currently have Windows 7 installed on drive C: I was doing things that I shouldn't and the OS became unusable. I want to format the drive and reinstall windows. I don't want to create a Windows.old folder, I want a clean formatted drive with a new installation of windows 7.
From the install CD I click on "customize" and then when prompted where to install Windows I click on "drive options" but from there, it will not let me remove, delete, or format any of my partitions as they are all grayed out. Why won't Windows 7 install let me format the drive for a clean install?
There's 4 partitions listed??
1. o data, unallocated
2. 100mb system reserved
3. 698gb primary HDD?
4. 0 data unallocated

A friend of mine had this problem and found that the 'upgrade' disk does not let you do this where my 'install' disk does. We switched disks and it was fine. I know there's a good chance this isn't your problem, but I thought I should post in case it is (or in case someone else with the problem checks for answers).

OldMX said:

Disk - Clean and Clean All with Diskpart Command

The question here is, can that be done (from the command line) DURING the windows setup process? Lets assume that the partition that contains the windows install is damaged and Windows can no longer be booted to get to a command prompt.

I've run into this exact situation. I had to uase a seconds windows 7 machine to delete the partitions on the drive before I could reinstall on it. It was quite frustrating. Bu default the partitioning step during install will no longer allow you to delete a partition that once had windows 7 installed on it

There must be a single computer/no working windows install solution to this...

If so, it might make a good seperat etutuorial because this situation is pretty unique in it's resolution.

Ah ok, boot to command prompt from install disk first...

Something else I missed was that there seems to be a difference between the full retail and upgrade versions of the disk. WHat's odd is I ran into this exact problem using a technet disk which I would be surprised to learn was an upgrade disk in reality... Wonder if the OEM disks also disallow this?

fseal said:

Ah ok, boot to command prompt from install disk first...

Something else I missed was that there seems to be a difference between the full retail and upgrade versions of the disk. WHat's odd is I ran into this exact problem using a technet disk which I would be surprised to learn was an upgrade disk in reality... Wonder if the OEM disks also disallow this?

It is my understanding that they are virtually identical, down to the last 1 and 0, except for the CD key.