DLL Hell is a term for the complications that arise when working with dynamic link libraries (DLLs) used with Microsoft Windows operating systems,particularly legacy 16-bit editions which all run in a single memory space.
DLL Hell can manifest itself in many different ways; typically when applications do not launch or work correctly. DLL Hell is the Windows ecosystem specific form of the general concept Dependency hell.
Solutions of DLLHell
Static linking
Windows File Protection
Running conflicting DLLs simultaneously
Portable Applications
Source: http://en.wikipedia.org/wiki/DLL_Hell