parrot328,
First run Delete Print Jobs to remove any stuck print job in the queue.
Disconnect the printer.
Download and run the patch(printer cleanup utility) until it prompts you to restart your computer.
Restart your computer. Make sure the printer is removed. Manual Printer Driver Removal
Download the Vista 32-bit drivers for Windows 7 32-bit or the Vista 64-bit drivers for Windows 7 64-bit. Install the Vista drivers in the Vista Compatibility mode You'll get a message, the printer is not connected. Connect the printer at this time(powered on).
Links to the patch/drivers can be found at...
Dell 966 Photo All-In-One Printer owners thread (W7)
Try reading...
Allow Wireless Printer Blocked by AVG 8.0 Firewall
Rick