Have you tried deleting the cache file to see if that clears up the error? Here are the steps that you can take for this:
common_installation_issues.pdf
If you continue to have this problem after clearing the cache file there might be a problem with your configuration. If this is the case you will need to follow these steps to undo any corruption that may have taken place.
showpost.php?p=12293&postcount=2
If you continue to have these errors after trying both of these please let us know so we can look into this further.