When I was browsing around on my Windows computer the other day, I noticed some files are displayed blue and others are black when I view them in My Computer. I'm sure there is a reason why they are different but am not sure why. Should I be concerned?
I can understand why you might be concerned.
There is nothing worse than that sinking feeling when you see something out of the ordinary on your Computer hard drive that you never saw before. Immediately you start to think of a virus or spyware.
The good news is, this is normal and your PC is fine.
What really is going on here is that you are viewing files that have been compressed by Windows. And, more than likely, one of your folder view options settings is set to display compressed NTFS files in color.
Let's take a look at what I mean.
Open up Windows Explorer (or just double click on My Computer).
The most common folder to see compressed files or folders is located in C:\Windows directory (except for Windows 7 & Vista).
As you can see normal files and folders are black and the compressed files and folders are blue.
The reason compression is being used, is to save disk space on your hard drive. Back in the early days of computers, having plenty of hard drive space was minimal compared to today's mammoth hard drives (see some of these drives here).
Those days, we did anything to free up disk space in Windows, including using compression to squeeze down the size of files and folders. Not all files can be compressed, such as mp3 or jpg and video files for example.
Fortunately with today computers and hard drives, compression is rarely needed if not at all.
But, sometimes the operating system will still compress files and folders, such as the ones inside C:\Windows folder. These files are good candidates for compression, since they are rarely accessed (compressing and decompressing files that are being accessed causes extra CPU usage…which is no longer a problem with multi core CPU's).
Control How Windows Explorer Displays Folder/File Name Colors
By default Windows Explorer is set to display compressed files in blue (and encrypted files in green).
This setting can be disabled in Windows Explorer (or My Computer) by clicking on Tools \ Folder Options and selecting the View tab.
Note: Folder Options can also be found in the Control Panel.
Under the Advanced settings: section, scroll down to you see the Show encrypted or compressed NTFS files in color settings, then click the box to check it for displaying colors or uncheck it to disable displaying of colors.
When finished, click the Apply to All Folders button and click Ok.
If you have enabled the option, any files or folders that are encrypted will be blue with non-encrypted files/folder displayed as black.
It's probably a good idea to keep the setting enabled, since it will help you recognize files and what state they are in, as oppose to not knowing and possibly realizing something funny is going on with your computer.