Can't extend unallocated space, system crashes [PLEASE HELP]

Ok, I am reinstalling win7 ultimate x64 on my C because it just crashed due to partitioning. I have my C and my unallocated space, I am trying to extend my C with unallocated space using a tool call minitool partition wizard. The tool says the C "Operation 'Resize partition' cannot be completed because drive C: is being used now" and a reboot is required, so I rebooted and BSOD. This already happen twice, this is my second time reinstalling win7 because of the partition issue, so how do I properly extend my c with unallocated space? I don't want to crash again and resinstall again, does a manually restore point fix BSOD if my third try fails?

Welcome to the forum. If it's a clean install when it asks were to install it gives an option to delete partition remove them all let Windows create what it needs

As Samuria mentioned you have to delete all partitions so the disk gets all raw. It then will create the necessary partitions.
https://www.sevenforums.com/attachmen...ep7.jpg?filter
https://www.sevenforums.com/attachmen...ep8.jpg?filter

Clean Install Windows 7

If the third party software asks you to restart the computer, don't because that's where something goes wrong. if there is unallocated space behind C drive, you can just use Disk Management, Windows built-in tool. to open it, you can press Windows key and R key, and then type "diskmgmt.msc" in the Run box. if the unallocated space are not contiguous, use third party software to move it and then use Disk Management to extend system drive.

I think you need to post the screenshot of the disk management.