diff --git a/sylk/configuration/datatypes.py b/sylk/configuration/datatypes.py
index 9204844..a5aedb2 100644
--- a/sylk/configuration/datatypes.py
+++ b/sylk/configuration/datatypes.py
@@ -1,179 +1,180 @@
 # Copyright (C) 2010-2011 AG Projects. See LICENSE for details.
 #
 
 import os
 import re
 import socket
 import sys
 import urllib
 import urlparse
 
 from application.python.descriptor import classproperty
 from application.system import host
 from sipsimple.configuration.datatypes import AudioCodecList, Hostname, SIPTransport
 
 
 class AudioCodecs(list):
     def __new__(cls, value):
         if isinstance(value, (tuple, list)):
             return [str(x) for x in value if x in AudioCodecList.available_values] or None
         elif isinstance(value, basestring):
             if value.lower() in ('none', ''):
                 return None
             return [x for x in re.split(r'\s*,\s*', value) if x in AudioCodecList.available_values] or None
         else:
             raise TypeError("value must be a string, list or tuple")
 
 
 class IPAddress(str):
     """An IP address in quad dotted number notation"""
     def __new__(cls, value):
         try:
             socket.inet_aton(value)
         except socket.error:
             raise ValueError("invalid IP address: %r" % value)
         except TypeError:
             raise TypeError("value must be a string")
         return str.__new__(cls, value)
 
     @property
     def normalized(self):
         if self == '0.0.0.0':
             return host.default_ip or '127.0.0.1'
         return str(self)
 
 
 class Port(int):
     def __new__(cls, value):
         try:
             value = int(value)
         except ValueError:
             return None
         if not (0 <= value <= 65535):
             raise ValueError("illegal port value: %s" % value)
         return value
 
 
 class PortRange(object):
     """A port range in the form start:end with start and end being even numbers in the [1024, 65536] range"""
     def __init__(self, value):
         self.start, self.end = [int(p) for p in value.split(':', 1)]
         allowed = xrange(1024, 65537, 2)
         if not (self.start in allowed and self.end in allowed and self.start < self.end):
             raise ValueError("bad range: %r: ports must be even numbers in the range [1024, 65536] with start < end" % value)
 
 
 class SIPProxyAddress(object):
     _description_re = re.compile(r"^(?P<host>(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})|([a-zA-Z0-9\-_]+(\.[a-zA-Z0-9\-_]+)*))(:(?P<port>\d+))?(;transport=(?P<transport>.+))?$")
 
     def __new__(cls, description):
         if not description:
             return None
         if not cls._description_re.match(description):
             raise ValueError("illegal SIP proxy address: %s" % description)
         return super(SIPProxyAddress, cls).__new__(cls)
 
     def __init__(self, description):
         match = self.__class__._description_re.match(description)
         data = match.groupdict()
         host = data.get('host')
         port = data.get('port', None) or 5060
         transport = data.get('transport', None) or 'udp'
         self.host = Hostname(host)
         self.port = Port(port)
         if self.port == 0:
             raise ValueError("illegal port value: 0")
         self.transport = SIPTransport(transport)
 
     def __getstate__(self):
         return unicode(self)
 
     def __setstate__(self, state):
         if not self.__class__._description_re.match(state):
             raise ValueError("illegal SIP proxy address: %s" % state)
         self.__init__(state)
 
     def __eq__(self, other):
         try:
             return (self.host, self.port, self.transport) == (other.host, other.port, other.transport)
         except AttributeError:
             return False
 
     def __ne__(self, other):
         return not self.__eq__(other)
 
     def __hash__(self):
         return hash((self.host, self.port, self.transport))
 
     def __unicode__(self):
         return u'%s:%d;transport=%s' % (self.host, self.port, self.transport)
 
 
 class Path(unicode):
     def __new__(cls, path):
-        path = os.path.normpath(path)
+        if path:
+            path = os.path.normpath(path)
         return unicode.__new__(cls, path)
 
     @property
     def normalized(self):
         return os.path.expanduser(self)
 
 
 class URL(object):
     """A class describing an URL and providing access to its elements"""
 
     def __init__(self, url):
         scheme, netloc, path, query, fragment = urlparse.urlsplit(url)
         if netloc:
             if "@" in netloc:
                 userinfo, hostport = netloc.split("@", 1)
                 if ":" in userinfo:
                     username, password = userinfo.split(":", 1)
                 else:
                     username, password = userinfo, None
             else:
                 username = password = None
                 hostport = netloc
             if ':' in hostport:
                 host, port = hostport.split(':', 1)
             else:
                 host, port = hostport, None
         else:
             username = password = host = port = None
         self.original_url = url
         self.scheme = scheme
         self.username = username
         self.password = password
         self.host = host
         self.port = int(port) if port is not None else None
         self.path = urllib.url2pathname(path)
         self.query_items = dict(urlparse.parse_qsl(query))
         self.fragment = fragment
 
     def __str__(self):
         return urlparse.urlunsplit((self.scheme, self.netloc, urllib.pathname2url(self.path), self.query, self.fragment))
 
     def __repr__(self):
         return '%s(%r)' % (self.__class__.__name__, self.__str__())
 
     url = property(__str__)
 
     @property
     def query(self):
         return urllib.urlencode(self.query_items)
 
     @property
     def netloc(self):
         authinfo = ':'.join(str(x) for x in (self.username, self.password) if x is not None) or None
         hostport = ':'.join(str(x) for x in (self.host or '', self.port) if x is not None)
         return '@'.join(x for x in (authinfo, hostport) if x is not None)
 
 
 class SRTPEncryption(str):
     available_values = ('opportunistic', 'sdes', 'zrtp', 'disabled')
     def __new__(cls, value):
         value = str(value)
         if value not in cls.available_values:
             raise ValueError("illegal value for SRTP encryption: %s" % value)
         return value