LinuxQuestions.org - yum not working

hi all,
i try to make yum as i need to remove some of my packages, it was work but it stops work, here is the output:

Code:

[root@abakhiet tmp]# yum -y remove asterisk* freepbx

Loaded plugins: fastestmirror, kmod

rpmdb: unable to join the environment

error: db4 error(11) from dbenv->open: Resource temporarily unavailable

error: cannot open Packages index using db3 - Resource temporarily unavailable (11)

error: cannot open Packages database in /var/lib/rpm

Traceback (most recent call last):

  File "/usr/bin/yum", line 29, in ?

    yummain.user_main(sys.argv[1:], exit_code=True)

  File "/usr/share/yum-cli/yummain.py", line 309, in user_main

    errcode = main(args)

  File "/usr/share/yum-cli/yummain.py", line 157, in main

    base.getOptionsConfig(args)

  File "/usr/share/yum-cli/cli.py", line 187, in getOptionsConfig

    self.conf

  File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 664, in <lambda>

    conf = property(fget=lambda self: self._getConfig(),

  File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 239, in _getConfig

    self._conf = config.readMainConfig(startupconf)

  File "/usr/lib/python2.4/site-packages/yum/config.py", line 804, in readMainConfig

    yumvars['releasever'] = _getsysver(startupconf.installroot, startupconf.distroverpkg)

  File "/usr/lib/python2.4/site-packages/yum/config.py", line 877, in _getsysver

    idx = ts.dbMatch('provides', distroverpkg)

TypeError: rpmdb open failed

So, what can i do ???
HELP please...