Just curious can you access it through the "computer managment snapin" ?
I am assuming you are on a Domain,just some thoughts off the top of my head do you have Audits set up in Group policy or user Manager on Domains via policies,Audit. Select the events you want to audit (e.g., success and failure for logons, file and object access, use of user rights, security policy changes.
Also what settings do you have set for when file fulls up etc. overwrite every 7 days "default"
Just some thoughts if anything else comes to mind I'll reply.
Sorry hope this helps a bit.