Many a times in windows XP and windows  7 your PC crashes and says a .dll file is missing.  You will recieve a “Couldn’t find ***.dll .. ” pop-up message at sometime. We used to format our computer if we cant find the solution. But now I want to give you some link where you can find almost all types of your DLL files and install it. You can download these files easily and ofcourse for free.

Search and download the missing or corrupt .dll or .ocx file from the above sites

Copy and paste those files in C:\WINDOWS\system32.