Normally when you get this error or one like it it can be due to a bad cache file or a corrupt config. For reference I'm listing the steps to take for both of these:
Clear the cache file:
common_installation_issues.pdf
Rename the configuration folder:
showpost.php?p=12293&postcount=2
You should start by trying to delete the cache file and if it does not resolve the problem you should move on to renaming the configuration folder. Post back and let us know if the issue persists beyond this.