...then you're sharing everything on your network.. Or is the printer not connected to your router? Just some thoughts here... If you've got shared computers, do you have network scanning enable on your antivirus programs? A mapped network drive maybe?

Which firewall do you have installed? How often are the "attacks" showing up in the firewall log.. (And NO, at this point, don't simply allow access to the attack locations.) Are you SURE it's the same IP address as your router and from your desktop ?

Since it's the wireless having problems, have you tried changing the wireless WPA password on the router and the laptop.. (Don't use WEP as it's easily crackable.)

Tried resetting the router? Or simply allow it to get a new IP address by turning off the power to the router for about 10 minutes, then power it up again and allow it to reinitialize.

Hope this helps.