When installing Windows 7 as a clean or custom install, it's necessary to ensure that only ONE partition is on the hard drive. I recommend this because the install goes much easier and less headaches, as you're experiencing now. Windows 7 is VERY fussy about having more than one partition to install to. I and a lot of other users have experienced this issue. It's a minor irritant really and once the OS is installed it's very easy to create more partitions.
Since it sounds as if the hard drive is garbled up the just use the "diskpart.exe' command during the install process and that will do a low-level reformat of the HDD. Wipe your hard drive completely clean, then in the hard drive windows of the install process create the size of partition you desire, usually 64GB is sufficient. That's taking 64,000,000 X 1.024 = 65,536,000 MB
Here's a handy tutorial:
To Open a Command Prompt at Boot
Then this to engage Diskpart:
In the elevated command prompt, type
diskpart and press
Enter. (see screenshot below)
In the elevated command prompt, type
list disk and press
Enter. (see screenshot below)
NOTE: This will give you a list of disk numbers to select from.
In the elevated command prompt, type
select disk # and press
Enter. (see screenshot below)
NOTE: You would substitute # for the disk number listed that you want to use clean or clean all on. For example, I want to use one of them on Disk 1 (from step 1) for my USB key drive, so I would type select disk 1 and press Enter.
To Use the Clean Diskpart Command
NOTE: See the green INFO box at the top of the tutorial for more information about this command. This command will wipe the HDD quickly.
A) In the elevated command prompt, type clean and press Enter. (see screenshot below)
NOTE: This will not take long to finish. Think of it as being like a quick format.
To Use the Clean All Diskpart Command
NOTE: See the green INFO box at the top of the tutorial for more information about this command. This command will wipe the HDD, and perform a secure erase. "Clean All" takes about an hour per 320 GB to finish running. It's best to only use this command if you wanted to help make sure that the data on the HDD cannot be recovered say when giving or selling the HDD to another person.
A) In the elevated command prompt, type clean all and press Enter. You will see the command prompt below as is until the "clean all" command is finished. (see screenshot below)
NOTE: This will take quite some time (several hours or more) to finish depending on how large the disk is since it is writing over each and every sector on it to zero. Think of it as being like a full or low level format
When finished, in the elevated command prompt, type
exit and press
Enter. Close the elevated command prompt.
Once you create that then finish the install. Windows 7 will create a 100MB partition for its own use; don't worry about it. It's there for a reason.
When you have installed Windows 7 and all correct drivers are installed then you should go ahead and create more more partitions if you want using the Disk Management feature of the Administrative Tools section of the Control Panel. Easy and quickly done.
