I think that you may just be experiencing an issue with your Macfilecache being corrupted. This can happen sometimes after installing an extension. To see if this is the problem please try the troubleshooting techniques for this issue as noted on this page:
Also, there is a further troubleshooting technique listed here for renaming or deleting the configuration folder. Please try deleting the cache file first and if that does not resolve the problem try the config folder. Let us know how this goes for you.