It seems like there could be some sort of corruption issue with your install. There are two things that you can try to help get past this issue.
The first is to delete Winfilecache, this file can have issues that will cause errors like this, especially after an install.
If removing this file and restarting does not do the trick for you there is one more thing which is to rename or delete your configuration folder. This will remove the extensions and get rid of any corruption present. If you do this you must re-install all of your extensions though. Here is a link to a page that lists these steps to take to do both of these. Please give this a try and let us know how it works for you.