What is a Rundll Error, Why Do I Have It, and How Can I Fix It?

If you've found a rundll error on your computer, it can be a huge pain. However, as long as you understand what the problem is, what caused it, and how to deal with it (and prevent it from coming back), you should be just fine.

What exactly is a rundll error?

Rundll.exe and Rundll32.exe are Windows operating system utilities that activate program files that have the ".dll" ("direct linking library") files. If you will think of each program's commands as a separate airplane cockpit, these files represent all the wires underneath the controls, as well as the automatic functions, that keep the engines running, tell the tail flap which way to turn, etc.

There are two different types of error in this case. The first is when Windows tries to use rundll to load another file, but cannot find that other file. The second is when Windows can't find rundll in the first place!

What causes these files to go missing?

Each of the above two types of problem often sprouts from the same source: malicious software
such as spyware, viruses, and Trojan horses. These programs may delete certain .dll files to aid their attack on your computer. They will also sometimes try to hijack, replace, or flat-out delete rundll32.exe itself.

The best way to keep your computer free of this kind of software is to run more than one anti-malware program. (More than three is a bad idea, though. This will slow down your computer and is just plain overkill.)

Unfortunately, malicious software can leave behind damage to the aforementioned .dll files, which are usually resident in the registry. A re-install and/or update of any affected programs, plus regular use of a registry cleaner/healer, is a good idea to keep your computer running smoothly.

I haven't found any spyware, Trojans, or other baddies on my computer--yet I'm still having problems. What gives?

There are a few other reasons for problems with your .dll files that can give you an error. Sometimes programs do not properly uninstall themselves.

If you encountered your problems after taking a program off of your computer, then you should re-install it, then uninstall while you have no other programs running. Restart your computer and see if it works any better.

It's also possible that you've accumulated a lot of dll "junk" over time, due to program updates, bad uninstalls, glitch software, or one of a hundred reasons that aren't your fault. It's important to learn about rundll error and registry issues if you want to keep your computer crash free and running smooth.