At one time or another we’ve all done it – looked in the Task Manager to close a frozen program or try to figure out what’s going on with our computer and discovered all of the various processes that are running. Even with the computer appears to be idle, there are processes running- it’s enough to make you think Big Brother is keeping tabs on you. So what’s with all of the rundll32.exe processes anyhow?

Rundll32.exe Basics:  What is it?

You’ve probably come across any number of different file types when using Windows. One of those types that appear in virtually every application is the .dll, or Dynamic Link Library, file. These files store application logic, and they are used by different applications. It's a library because it's a resource to different programs running on your PC, each of which may be able to access a library as needed.  Since they're only accessed when they're called for, the system saves energy and memory.  Unfortunately for the .dll files, they can’t be launched directly, and instead have to rely on the rundll.32 process to make them functional.

So that's what it is.  It's a program that is executable, hence the .exe ending.  It runs automatically on startup, and during the course of your using the computer, it accesses a given .dll as requested by a given program.  Without it, programs that rely in their libraries to store extra data can't function right.  What happens when the rundll.exe can't find or open the requested library?  You get a rundll error.

These errors are common because there are thousands and thousands of dlls out there. Any number of these could have a problem that translated as an error for you when rundll doesn't open it.

Assessing Errors

What is the Command Line?

There is a possibility of spyware or malware disguising itself as a rundll.exe process, but you should be able to sniff this out with a security sweep of your computer. In Windows Vista or Windows 7, however, you’re able to see the full command line for the application, so you can get to the bottom of each one.

To see the command line of the rundll.exe process, open the Task Manager by clicking CTRL+SHIFT+ESC, or accessing "Task Manager" from the search field.  Click on View in the Task Manager window. In the View menu, click on Select Columns. One of the options you’ll have is to click on Command Line. Select this box and you’ll be able to see the full path for each file in the Task Manager window.

When you click OK, you’ll be able to see the path for each file cheked.  Here, the path for the rundll32.exe includes another DLL as what is actually being run.

To learn even more about the file the rundll32.exe file is running, right-click on the file command line in the Task Manager window. Click on Open File Location. A window will open that shows you where that file is located in your computer. If you were to hover your mouse over the file name in this view, you’re able to see a full description and other details about the file. The file description and the company name will be the most useful is figuring out what the file is doing on your computer.

Hint: If there is no or very limited information about the file, you can always search for the file name online or ask about it on a technical forum to get more information.

To Disable or Not

Now that you know what the file is, you’ll have the option to disable the rundll32.exe file.  Doing this isn't usually recommended because it could interfere with the way your system runs, but sometimes disabling rundll.exe is a way to temporarily disable the problematic element, giving you time to find out what the root of the problem is.  Once the cause of the error is isolated, you can take the steps necessary to disable it and then re-enable rundll.exe.

Using the Process Explorer in Vista and Windows 7

If you’d like to be able to navigate through your processes a bit more cleanly, you can download a free program from Microsoft called Process Explorer.  Follow the instructions on the Microsoft page to download the Process Explorer. Once you’ve completed the download correctly, start up the program. One of the first things you’ll want to do once you’re able to see all of the processes is open the File menu and then select Show Details for All Processes.

Once this option is selected, you’re able to simply hover over the file names in the application and see a box pop up with all the information about that particular file.

If you want to see even more about the file than the hovering allows, simply right-click on the file name and you’ll be able to see Properties in your menu of options. Click on Properties and you’ll be treated to the full gamut of information about the file. In the Image folder, you’ll be able to see the command line that tells you more about what that rundll32.exe is actually running.

If the command line and details about the process tell you that it was launched from a real application, in particular one that you use quite often, you don’t want to do anything to that process. For example, in the example above, the rundll32.exe file is actually part of the NVIDIA control panel, so there is no reason at all to do anything to the file – it’s part of the video display and presumably doing its job correctly.

Stopping a Process from Running

If you’re looking at the details of your rundll32.exe file and feel like it’s causing a problem immediately, you can kill the process in a couple of different ways. The first is to click on the button labeled Kill Process while you’re looking at the details in Process Explorer.

If you’ve been working out of the Task Manager window, you have the option to stop the process as well. In this case, the End Process button will kill the application if you select it while you’re looking under the Processes tab of the Task Manager.

Stopping an Application from Running on Startup

To disable the processes from the very beginning, or to keep them from starting up at all, you can manage the startup entry associated with it.  A startup entry is a command that tells Windows to launch a given program or process when the computer starts.  Controlling certain non-vital startup entries is easy.  Just type "msconfig" in the Search box at the Start Menu.

Open the program and click on the Startup tab. You’ll see all of the processes that are currently slotted to start when you turn on the computer.

Double-check that you have the right program by looking in the Command line. Once you’ve found the right file, simply uncheck the box next to the file name and click OK.  You'll have to reboot your system for the changes to take effect, but once they do, this will disable the process from starting automatically.