When an antivirus program is installed on the computer, it is capable of scanning all files on the computer, as well as each file individually. Each file can be scanned by right-clicking the file and choosing the option to scan the file for viruses.

For example, in this picture, we've highlighted the my-file.DLL file and right-clicked the file to see the 'Scan with AVG' option in the file menu. When this option is selected, AVG Antivirus opens and scans that file for any viruses.

Occasionally you might experience a flawed software installation, which may be due to a problem encountered during the install process. This can prevent your operating system from associating your DLL file with the right software application, affecting what is known as "file extension associations".

Sometimes, simply reinstalling Windows will solve your problem, properly associating your DLL with Windows. Other times, poor software programming on behalf of the software developer can cause problems with file associations, and you may need to contact the developer for further assistance.

Tip: Try upgrading to the latest version of Windows to ensure you have the latest patches and updates installed.

It may seem too obvious, but many times your DLL file itself might be the cause of the problem. If you received the file through an email attachment, or downloaded from a website and it was interrupted (e.g. power outage or other reason), it may have corrupted the file. If possible, try obtaining another fresh copy of your DLL file and attempt to open it again.

Caution: A corrupt file could also be collateral damage of a previous or existing malware infection on your PC, that's why it is essential that you keep an updated antivirus running on your computer at all times.

If your DLL file is related to a piece of hardware on your computer, you might need to update your device drivers associated with that hardware in order to open it.

This problem is commonly related to multimedia file types that depend upon a piece of hardware inside of your computer to be successfully opened, such as a sound card or graphics card. For example, if you are trying to open an audio file, but failing to open it, you might need to update your sound card drivers.

Tip: If you are receiving an error message related to a .SYS file when attempting to open your DLL file, it's likely your problem is related to corrupt or outdated device drivers that need to be updated. Using a driver update software such as DriverDoc can help make this process much easier to complete.

If all other steps fail, and you are still experiencing problems opening DLL files, it might be due to a lack of available system resources. Some versions of DLL files can require substantial resources (eg. Memory/RAM, processing power) to be properly opened by your computer. This is quite common if your computer hardware is older, and you are using a much newer operating system.

This issue can occur when your computer is having a hard time keeping up because the operating system (and other services running in the background) might be consuming too many resources for your DLL file to open. Try closing all applications on your PC before attempting to open your DLL. Freeing up all of the available resources on your computer provides the best environment for attempting to open your DLL file.

If you've tried all of the steps above, and your DLL file still won't open, you might be due for a hardware upgrade. In most cases, even if you have older hardware, processing power is still more than adequate for most user's applications (unless you do a lot of CPU resource-intensive work such as 3D rendering, financial / scientific modeling, or intensive multimedia work). Therefore, it's likely that your computer is lacking the necessary amount of memory (more commonly referred to as "RAM", or random access memory) to complete the file opening task.

Try upgrading your memory to see if that helps you open your DLL file. These days, memory upgrades are quite affordable and very easy for even the casual computer user to install in their PC. As a bonus, you'll probably see a nice performance bump in other tasks carried out on your computer.