I guess then, the next logical option is to ensure that your laptop is using the same group as the other machines and that discovery is switched on.
First of all try this: Start --> Control Panel --> Network and Internet --> Network and Sharing Center --> Change advanced sharing settings. Make sure network discovery is switched on. You may also wish to ensure file and printer sharing is switched on.
Having applied those changes, try browsing to the NAS box again.
If that didn't work, on one of the other machines, check the workgroup it's connected to. Right-click My Computer, choose Properties. On Windows 7/Vista, click the Advanced system settings link. Go to the Computer Name tab of the System Properties box. Click the Change button to see the currently configured workgroup. On your laptop, follow a similar process only this time, change the workgroup to match the other computers. Reboot your laptop.
Any better?