this is using GHC 7.4.1 and using the cabal which came with the latest haskell platform. I wiped clean my$HOME/cabal and $HOME/ghc, $HOME being %AppData%. In $HOME/cabal/configI set those options: library-profiling: True user-install: True Any idea? emmanuel ... [8 of 8] Compiling Network ( Network.hs, dist\build\Network.p_o ) Network.hs:291:13: Warning: Pattern match(es) are overlapped In a case alternative: _ -> ... Registering network-2.4.0.1... Installing library in C:\Users\emmanuelto\AppData\Roaming\cabal\network-2.4.0.1\ghc-7.6.1 Registering network-2.4.0.1... cabal: Error: some packages failed to install: network-2.4.0.1 failed while downloading the package. The exception was: DeleteFile "C:\\Users\\EMMANU~1\\AppData\\Local\\Temp\\network-2.4.0.1-2768\\network-2.4.0. 1\\conf5576.lnk": permission denied (Access is denied.)