OS X 10.8.4 Flash Installation Error Message

[Roadlesstrvled]

Have repeatedly encountered this error message at about 50% mark.   Someone fluent in Computerese able to assist me?

BTW: The article suggesting a clean restart by deleting older versions referenced a LIBRARY folder ... which I do not seem to have anywhere.  Older OS X had a "library" folder, but not the one I am using now.  Wonder where it went?

[C_F_McBlob]

ALL versions of OS X have a Library folder. In fact, there are at least TWO (2). One for the Mac HD, and one for each user account. (Hold the "Option" key when you click "Go" from the Finder menu to see it - it's hidden otherwise)