ERROR: could not load library "libumfpack"

Today I went after a long time compiling the DLL and got the following error.

...
dates/Dates.jl
sparse/sparse.jl
LoadError("sysimg.jl",344,LoadError("sparse/sparse.jl",42,LoadError("sparse\\umfpack.jl",75,ErrorException("error compiling anonymous: could not load library \"libumfpack\"\nThe specified module could
 not be found.\r\n"))))
ERROR: LoadError: failed process: Process(`'C:\Users\martin.florek\Develop\Julia-0.5.1\bin\julia' -C core2 --output-ji libAPI.ji --output-o libAPI.o -J inference.ji --startup-file=no sysimg.jl`, Proce
ssExited(1)) [1]
 in pipeline_error(::Base.Process) at .\process.jl:616
 in run(::Cmd) at .\process.jl:592
 in (::##2#3{Bool,String})() at c:\Users\martin.florek\Develop\Projects\TIMcompile\CompilePrototype\051\build_sysimg_tim.jl:86
 in cd(::##2#3{Bool,String}, ::String) at .\file.jl:48
 in #build_sysimg#1(::Bool, ::Bool, ::Function, ::String, ::String, ::String) at c:\Users\martin.florek\Develop\Projects\TIMcompile\CompilePrototype\051\build_sysimg_tim.jl:53
 in (::#kw##build_sysimg)(::Array{Any,1}, ::#build_sysimg, ::String, ::String, ::String) at .\<missing>:0
 in include_from_node1(::String) at .\loading.jl:488
 in process_options(::Base.JLOptions) at .\client.jl:265
 in _start() at .\client.jl:321
while loading c:\Users\martin.florek\Develop\Projects\TIMcompile\CompilePrototype\051\build_sysimg_tim.jl, in expression starting on line 214
The system cannot find the file specified.

Before that (3 weeks back), I had no problems.
I have version 0.5.1 and OS Windows 8.1.
Where is the problem, please?

The problem is here:

Try loading libumfpack from plain Julia instead of through the custom sysimg build. If that works, then there’s probably a PATH or dependency issue. Use DependencyWalker or other similar tools to debug.