Add/remove pirut error

Whenever I try to open the Package Manager through the extended right click menu and pirut either to add or to verify applications or if I try to update my program list, I get immediately an error message like the following:

Component: pirut
Summary: TBc0c9275d config.py:680:_getsysver:TypeError: rpmdb open failed

Traceback (most recent call last):
File "/usr/sbin/pirut", line 476, in <module>
main()
File "/usr/sbin/pirut", line 469, in main
pm = PackageManager(options.config, options.onlyrepo)
File "/usr/sbin/pirut", line 63, in __init__
GraphicalYumBase.__init__(self, False, config)
File "/usr/lib/python2.5/site-packages/pirut/__init__.py", line 129, in __init__
plugin_types=(yum.plugins.TYPE_CORE,))
File "/usr/lib/python2.5/site-packages/yum/__init__.py", line 113, in doConfigSetup
errorlevel=errorlevel)
File "/usr/lib/python2.5/site-packages/yum/__init__.py", line 159, in _getConfig
self._conf = config.readMainConfig(startupconf)
File "/usr/lib/python2.5/site-packages/yum/config.py", line 613, in readMainConfig
yumvars['releasever'] = _getsysver(startupconf.installroot, startupconf.distroverpkg)
File "/usr/lib/python2.5/site-packages/yum/config.py", line 680, in _getsysver
idx = ts.dbMatch('provides', distroverpkg)
TypeError: rpmdb open failed

Local variables in innermost frame:
installroot: /
ts: <rpmUtils.transaction.TransactionWrapper instance at 0x85bcf6c>
distroverpkg: redhat-release

This is very annoying and it makes me think about changing to Mandriva.
Can anybody help me ?