-parallel and error"failed to load interface for ..."

[Khamenia, Valery]

Hi ghc world,

why option -parallel leads to error while without this option everything was
compiled OK?

--------------------Custom Tool: ghc--------------------
Command   : D:\pkg\ghc\ghc-5.04.1\bin\ghc.exe -parallel -package concurrent
"Examples.hs" -o a.exe
Directory : "C:\tmp\Haskell\try"

Examples.hs:2:
    failed to load interface for `Prelude':
	Could not find interface file for `Prelude'

Examples.hs:5:
    failed to load interface for `Parallel':
	Could not find interface file for `Parallel'
---------------------------------------------------------------------------
regards,
Valery A.Khamenya
Bioinformatics Department
BioVisioN AG, Hannover