HELP!!! Huge problem Cannot access control panel after upgrade

Hi,

We have just uploaded cms builder 1.36 as an update to our original Instant Realty install however we now find that when we attempt to log in we get an error relating to invalid product key, however when we insert the newly provided key we get the same error, I have checked the permissions on the files and folders which seem correct but we cannot gain access to the control panel (nor can any of our advertisers) due to this issue of it not accepting the product key. I have also tried the origional product key which also is not accepted, I suspect it may be a permissions issue somewhere but cannot find it.

This is obviously very embarassing for us and causing a major problem, if someone could provide some help or advice it would be appreciated, I am assuming that the newly provided key is correct and not the issue as I have also tried entereing a different CMS Builder key to get the same error.

I am about to recheck permissions for the third time but any help in the meantime would be appreciated.

Thanks in advance