Hi,

1. Windows 7 Extend Volume
2. Windows 7 Shrink Volume Problem
3. Shrink A Basic Volume In Disk Management
4. Windows 7 Shrink Volume Disabled

I would suggest you to try these steps and check if it helps.

Method 1:

There was a time when we used to install create, delete, extend and shrink partitions in Windows XP. Unlike Windows XP, modern Windows operating systems Vista and Windows 7 packs-in decent set of tools to create, delete, extend and shrink partitions without having to use third-party tools. How to Fix: Can't Shrink Volume in Windows 7, 8, 10 The first thing you need to do is disable some services and files in use by operating system. The big culprits here are restore points (system protection), virtual memory, and system log files. Mar 20, 2013  There was a time when we used to install create, delete, extend and shrink partitions in Windows XP. Unlike Windows XP, modern Windows operating systems Vista and Windows 7 packs-in decent set of tools to create, delete, extend and shrink partitions without having to use third-party tools. Windows 7, Windows 8, 8.1, 10, and Vista include a built-in functionality in Disk Management to shrink and expand partitions. No more 3rd party utilities needed! It’s worth noting that many third-party utilities will be more feature-rich, but you can do the very basic stuff in Windows without adding anything new. This guide talks about how to shrink volume without data loss in Windows 10/8/7/Vista/XP and provides four methods to shrink/resize volume on hard drive, USB drive, virtual disk, etc.

Perform check disk on C drive to check if there are any harddrive errors

a.Click on start and then type cmd.exe in the start search and press enter.

b.Right click on cmd.exe and click on Run as administrator.

c.In the command prompt, type the following command and press enter.

Chkdsk /f

Note: You may be prompted with a yes/No question. Type yes and hit enter.

d.Restart the computer so that the check disk initiates.It will take about half an hour to complete the error checking process. Do not restart the computer when the check disk in progress.

Note: While performing chkdsk on the hard drive if any bad sectors are found on the hard drive when chkdsk tries to repair that sector if any data available on that might be lost

Method 2:Turn of the system protection on c drive.

a.Click on start.

b.Right click on computer and click on properties.

c.Click on Advancedsystem settings on the left pane

d.Click on system protection tab.

Windows 7 Extend Volume

e.In the protection settings, click on C drive and then select Configure.

f.Then place a check mark on Turn off system protection.

g.Press ok and restart the computer.

Once done, try to shrink the volume C and check.

For reference:

Windows 7 Shrink Volume Problem

Easily Shrink a Volume on a Windows 7 Disk

http://technet.microsoft.com/en-us/magazine/gg309169.aspx

Shrink A Basic Volume In Disk Management

Method 3:Run a virus scan on the computer to make sure it is virus free

Safety Scanner Disclaimer: There could be a loss of data while performing a scan using Microsoft safety scanner to eliminate viruses if any.

Windows 7 Shrink Volume Disabled

Hope it helps.