EFS in a domain expires after three years

Here’s info on how to backup and remove your old domain certificate, generate and install a new one.

Hopefully, no one in your domain uses EFS.  If so, it can be a total pain if your certs are expired.

http://msmvps.com/blogs/alunj/archive/2007/03/24/efs-in-a-domain-expires-after-three-years.aspx

Also, read here: http://support.microsoft.com/kb/929103