A DLL (Dynamic Link Library) is a grouping of subroutines called by another program. In order for the program to call it, it has to know where to find it. There are different ways this can be accomplished including: it can be in a folder in the "path", it can be in the same folder as the calling program, or it can be pointed to from the registry. But what can not done is to search the entire hard drive to find it in another folder. If you have two files with the exact same name then they must have been in two different folders. If something didn't work after you deleted one then at least one program expected to find it in that folder you deleted it from.