Are you using Windows Live OneCare? if you turn off the Windows Live OneCare firewall can you access the printer? If so, then you may need to tweak the OneCare firewall settings - try the following on each PC with the issue that has OneCare installed:
Open OneCare on each of the computers.
Click Change Settings
On the firewall tab, click configure firewall
If the network is shown as Public, click Change Location to change it to "Home or Work."
Click the Advanced Settings button
Click Network connections tab.
If there are multiple active connections shown, you may need to disable the extras in your Windows network connections settings. (Network and Sharing Center, manage connections, in Vista; Right click My Network Places and select Properties on the Start menu in XP)
On the Ports and Protocols tab, add a check mark next to File and Printer Sharing - for subnet and Internet if the first setting alone (after all of the above are verified) does not allow Sharing to work.
If all of the above fail *and* the printer works when the firewall is turned off, please contact support.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
If the printer can't be accessed with the OneCare firewall off, then it is not likely to be a OneCare issue. It may require you to configure the printer for your wireless network with the correct security key.
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator
