Missing Permissions in Advanced tab

[imheywood]

We have a folder which holds some Sage Payroll data on Windows 2003 Server. At random times this folder becomes inaccessible. This folder is not shared but the folder above it is. Everyone has Full control of the folder.
If you click on the Advanced button though there is no entries shown in the Permissions tab. You can add the Everyone group back in and then access is restored. This will work again either for just a few minutes or days before we have to add the Everyone group again.
Any ideas??

 

[tfg13]

Any reboots that are taking place that might cause this? Any security database settings that are in place? Any group policies you have that might cause this behaviour?