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:
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.
If you continue to have these errors after trying both of these please let us know so we can look into this further.