There are a number of posts related to accessing and/ copying issues between Windows Vista / 7 and AirPort Disks. Two potential solutions being forwarded are: 1) Changing the LAN Manager authentication level, and/or 2) Disabling the Windows Search feature.
To change the LAN Manager authentication level:
- From the Windows Vista / 7 desktop, click Start
- Search for: security
- Click 'Local Security Policy'
- Goto Local Policies > Security Options
- Under Policy, double-click 'Network security: LAN Manager authentication level'
- Change level to: Send LM & NTLM responses
- Under Policy, double-click 'Network security: Minimum session security for NTLM SSP based (including RPC) clients'
- De-select 'Require 128-bit encryption'
- Click OK
To disable Windows Search:
- Start > Control Panel > Programs > Programs & Features
- On the right-hand side, click "Turn Windows features on/off"
- Scroll down, and de-select "Windows Search".
- Press OK, close all windows and restart.
A third "solution," that has worked for me, is verify that both the AirPort base station and the Win7 PC are using the exact same Workgroup Name. In my case, I use "WORKGROUP" (without the quote marks) for this name.
From the AirPort Utility, you would enter this value on the Disks > File Sharing tab.
On Win7, Start > Control Panel > System and Security > System > Change Settings > Change > Workgroup