Verified answer

Rundll.exe files are systems process directly related to your computer's Windows Registry. All Dll files are a part of vast library that contains code and data that is shared by many programs. This helps to produce speed and memory efficiency in your operating system by reusing the same code or file to run many functions by various programs. An error occurs when program aren't allowed to access this code.

To fix the file, check this tutorial out:

http://www.delete-computer-history.com/rundll-erro...

Msdia80.dll

Hey, Don't worry about anything, I just have the same problem. All AVG users are. It's just kind of like a bug, or the update is missing some files. The best recommended thing I suggest you should do is nothing. You might mess up AVG, and waste your time. They will probably update this soon. Your Antivirus and Spyware protection and all those stuff will still be working properly, so you shouldn't worry. The bad thing is you will have the ! on your grayish AVG icon. If you do not trust me you can search 'bin file missing' on Yahoo! Answers. You can see a list of questions exactly like yours posted somewhere 6 hrs, 7 hrs, 5 hrs ago, or somewhere today. It is just a false update made by grisoft. Just be patient and it'll be updated, and everything will be working properly again. Good Luck! Kevin Don't worry!

DLL files are needed for the programs you use. Sometimes... several different programs can be using the same DLL file. In my opinion, you should not delete it. It's only taking up about 0.001% of your hard drive space and on the other hand, if you did delete it, some of your programs may not work any more.