I am facing the same issue

Could not load the DLL d:\MSSQL\Binn\xp_base64decode.dll, or one of the DLLs it references. Reason: 193(%1 is not a valid Win32 application.).

I believe its again to do with 64bit environment issue.

Is the 64 bit xp_base64decode.dll & xp_base64encode.dll readily available?