Missing Indices File when trying to commit or branch

[simpsus]

$bzr commit
bzr: ERROR: No such file: u'/home/[appDir]/.bzr/repository/indices/f63c8fed795293407ddabb9e133bb0e0.rix': [Errno 2] No such file or directory: u'/home/[appDir]/.bzr/repository/indices/f63c8fed795293407ddabb9e133bb0e0.rix'

The Traceback from bzr -Derror ci is:

Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 716, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 911, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 547, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.6/dist-packages/bzrlib/builtins.py", line 2789, in run
    exclude=safe_relpath_files(tree, exclude))
  File "/usr/lib/python2.6/dist-packages/bzrlib/decorators.py", line 192, in write_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/workingtree_4.py", line 226, in commit
    result = WorkingTree3.commit(self, message, revprops, *args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/decorators.py", line 192, in write_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/mutabletree.py", line 228, in commit
    *args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commit.py", line 303, in commit
    old_revno, new_revno = self._check_out_of_date_tree()
  File "/usr/lib/python2.6/dist-packages/bzrlib/commit.py", line 505, in _check_out_of_date_tree
    if self.branch.repository.has_revision(first_tree_parent):
  File "/usr/lib/python2.6/dist-packages/bzrlib/decorators.py", line 138, in read_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/repository.py", line 1249, in has_revision
    return revision_id in self.has_revisions((revision_id,))
  File "/usr/lib/python2.6/dist-packages/bzrlib/decorators.py", line 138, in read_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/repository.py", line 1259, in has_revisions
    [(rev_id,) for rev_id in revision_ids])
  File "/usr/lib/python2.6/dist-packages/bzrlib/knit.py", line 1135, in get_parent_map
    return self._get_parent_map_with_sources(keys)[0]
  File "/usr/lib/python2.6/dist-packages/bzrlib/knit.py", line 1154, in _get_parent_map_with_sources
    new_result = source.get_parent_map(missing)
  File "/usr/lib/python2.6/dist-packages/bzrlib/knit.py", line 2931, in get_parent_map
    for node in nodes:
  File "/usr/lib/python2.6/dist-packages/bzrlib/knit.py", line 2878, in _get_entries
    for node in self._graph_index.iter_entries(keys):
  File "/usr/lib/python2.6/dist-packages/bzrlib/index.py", line 1272, in iter_entries
    self._reload_or_raise()
  File "/usr/lib/python2.6/dist-packages/bzrlib/index.py", line 1267, in iter_entries
    for node in index.iter_entries(keys):
  File "/usr/lib/python2.6/dist-packages/bzrlib/index.py", line 612, in iter_entries
    if self._nodes is None and len(keys) * 20 > self.key_count():
  File "/usr/lib/python2.6/dist-packages/bzrlib/index.py", line 704, in key_count
    self._read_and_parse([_HEADER_READV])
  File "/usr/lib/python2.6/dist-packages/bzrlib/index.py", line 1128, in _read_and_parse
    self._size)
  File "/usr/lib/python2.6/dist-packages/bzrlib/transport/__init__.py", line 655, in readv
    return self._readv(relpath, offsets)
  File "/usr/lib/python2.6/dist-packages/bzrlib/transport/__init__.py", line 667, in _readv
    fp = self.get(relpath)
  File "/usr/lib/python2.6/dist-packages/bzrlib/transport/local.py", line 167, in get
    self._translate_error(e, path)
  File "/usr/lib/python2.6/dist-packages/bzrlib/transport/__init__.py", line 307, in _translate_error
    raise errors.NoSuchFile(path, extra=e)

[simpsus (bastian-kennel)]

Ubuntu Intrepid 2.6.28-15-generic
Bazaar (bzr) 1.13.1
  Python interpreter: /usr/bin/python 2.6.2
  Python standard library: /usr/lib/python2.6
  bzrlib: /usr/lib/python2.6/dist-packages/bzrlib
  Bazaar configuration: /home/bastian/.bazaar
  Bazaar log file: /home/bastian/.bzr.log

The Project Directory is included in ~/DropBox and is thus shared and used on another computer (commits done on both sides). .bzr is also shared via DropBox. This setup worked for > 6 months.