This problem is very common, as generally the system partition is not large enough (waste free space if you won't use a large system partition). Windows continuously install updates and you have to install other applications to the system partition, browser caches, restore points of system protection, temporary files also eat up your free space very quickly.
The symptom of "c drive out of space"
Windows XP and Server 2003 displays the low disk space warning as "You are running out of disk space on Local Disk (C:). To free space on this drive by deleting old or unnecessary files, click here."
If Windows 7 C drive is out of space, it will be shown in red as below:
If C drive running out of space, it will cause many problems, such as:
1. Hard disk drive is not big enough to accommodate all your needs, such as Windows update/upgrade, install programs.
2. Windows operating system is running much slowly.
3. System crash if the free space is extremely low.
How to solve low disk space problem?
To resolve "c drive running out of space" issue, follow each of the below steps.
1. Clean up the hard disk drive Run Windows Disk Cleanup function by clicking on the Low Disk Space popup. This tool will scan your drives and look for files that you can safely erase. Usually this will be little help.
2. Remove programs. Consider removing programs that you don't use and moving large media files (videos, music, graphics) to other partition, but it cost a long time. (Don't try to delete Windows files or those you are not familar with)
3. Extend partition (add disk space to C drive). You may use partition manager software to resize partition and it is the most time-saving and easiest way. Shrink other existing data partition to extend the system partition without deleting or reformatting.
Extend partition to solve C drive out of space problem
Step 1, Launch Partition Magic Server, you'll see all disks and partitions that connected to your Server and free space, used space and other properties of each partition.
Right-click the data partition and select "Resize", in the pop-up window, drag the left border rightwards to shrink it.
There will be some Unallocated space behind the system partition.
Step 2, Right-click the system partition and select "Resize", in the pop-up window, drag the right border rightwards to hold the Unallocated space.
Click "Apply" to proceed, done.
Now you have a "new" Server that can be used for a long time again.
Too complicated? Check the one-click solution to allocate free space from one partition to another, lol.
If VMware VMDK C drive runs out of space, refer how to extend C drive on VMware Server?