Installing additional software to the operating system can overwrite shared system files such as dynamic link libraries (.dll files) and executable files (.exe files), for MS Windows.
Steps

Step 1. Missing DLL files that somehow disappear, cause your computer to start acting strange, such as not logging off properly
Run a system disk scan with Norton Antivirus software. Norton has a tool called "WinDoctor" that does the repairs automatically. One suggestion is that if you remove Norton to install another free antivirus program, keep Norton Utilities / WinDoctor and Speed Disk to defragment.

Step 2. Always run a review or scan of everything you download before opening it
Remove programs that you don't use or need. Too many programs can crash your computer. Defragment your computer periodically. Every time you download or remove programs, music, or other files, plus normal file creation, the computer becomes fragmented and its own functions slow down and confuse. "When system files such as. Sys, dll., Ocx., Ttf., Fon., And exe. Are overwritten, system performance becomes unpredictable, programs behave erratically, and operating system crashes ".

Step 3. If you can determine that you are missing one or more DLL files, that they can be identified, and that they can be replaced, Google a site that offers a free DLL file download service
Download and unzip the file on your desktop. To do this, you will need Winzip or WinRAR to extract the archive.

Step 4. Now you must locate the DLL file in the appropriate folder or subfolders where the system files are stored
One way to find the program that is missing the file is by entering it into Google.

Step 5. q_encutl.dll + program '
Take, for example, the message that the 'Norton Windoctor' is likely to throw up: "C: Program FilesCommon FilesInstallShieldProfessionalRunTime81

Step 6. Intel32DotNetInstaller.exe "Cannot access a required file," mscoree.dll
"Download the mscoree.dll file.

Step 7. Using 'Windows Explorer', you can in this case go to Local Disk [C] Program Files / Common Files / InstallShield / and check the subfolders until you find, Professional / Run Time / Intel32
Then cut and paste or copy the DLL file into the folder. By copying instead of cutting and pasting, you can put the DLL download in the documents folder as an extra copy.

Step 8. You can also go to the "Run" option and type "SFC"
If this doesn't work, write the missing DLL and manually overwrite it with the Windows installation CD.
Advice
- If you don't have unzipping software you can find one for free at
- Sometimes software comes with DLL files included, so installing it can fix other programs as well.