checkout Error on cygwin

["Joan Ripoll Balaguer" <joan.ripsa@gmail.com>]

$ git version
git version 1.5.1.1.135.gf948

$ git status
# On branch cajal/20070201
nothing to commit (working directory clean)

$ git checkout master
      6 [main] git-read-tree 2640
C:\cygwin\usr\local\bin\git-read-tree.exe: *** fatal error - could not
load shell32, Win32 error 487

Then:

$ git status
# On branch cajal/20070201
# Changed but not updated:
#   (use "git add/rm <file>..." to update what will be committed)
 (A lot of files)
#
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
 (A lot of files)


Now I would have an clean status:

$ git reset --hard HEAD
fatal: unable to create '.git/index.lock': File exists

$ rm .git/index.lock

$ git reset --hard HEAD

$ git status
# On branch cajal/20070201
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
(A lot of files)
nothing added to commit but untracked files present (use "git add" to track)

$ git clean -x
Removing ... (a lot of files)

Any suggestion?

-- 
Joan Ripoll
joan.ripsa@gmail.com