How to solve "You might not have permission to use this network resource"

If you have shared folder or drive in a PC but it can not accessed from other computers, then check this:

1. Open Control Panel --> Administrative Tools --> Local Security Policy.

2. Select "Local Policies" --> "User Right Assignment" --> "Deny Access to this computer from the network..."
    Remove any User in that box.

3. Select "Local Policies" --> "User Right Assignment" --> “Access this computer from the network”.
    Make sure "Everyone" exist.

How to Enable and Disable Automatic Log Off Windows XP

Right click the Desktop > Properties, click Screen Saver tab.  To disable Uncheck the "On resume, password protect" or "On resume, display Welcome screen" option. To enable check it. Also look at the options for your Screen saver.