Appears Adaware and System Mechanic were only doing the job they are designed for.
What is a DLL?
A DLL is a library that contains code and data that can be used by more than one program at the same time. For example, in Windows operating systems, the Comdlg32 DLL performs common dialog box related functions. Therefore, each program can use the functionality that is contained in this DLL to implement an Open dialog box. This helps promote code reuse and efficient memory usage.
Looks like it has been a link to another program or link to a website that is no longer required and it has been removed safely. As you say it doesn't appear to have any effect on your PC so I wouldn't worry any further about it.