yum troubles

hello list,
I keep on having problems with yum. The next message shows when I try $ yum check-update or yum update

]$ yum check-update
Traceback (most recent call last):
 File "/usr/bin/yum", line 30, in ?
   yummain.main(sys.argv[1:])
 File "/usr/share/yum/yummain.py", line 163, in main
   (log, errorlog, filelog, conf, cmds) = parseCmdArgs(args)
 File "/usr/share/yum/yummain.py", line 75, in parseCmdArgs
   conf=yumconf(configfile=yumconffile)
 File "/usr/share/yum/config.py", line 48, in __init__
   self.cfg.read(configfile)
 File "/usr/lib/python2.3/ConfigParser.py", line 263, in read
   self._read(fp, filename)
 File "/usr/lib/python2.3/ConfigParser.py", line 456, in _read
   raise MissingSectionHeaderError(fpname, lineno, `line`)
ConfigParser.MissingSectionHeaderError: File contains no section headers.
file: /etc/yum.conf, line: 1
'\xef\xbb\xbf[main]\n'

Considering there could be multiple installation faults I dowmlaoded and installed yum again, but that does not solve the problem.
Getting desperate,
Peter.