I always get 'add new hardware' box when starting my computer.

It actually started when I installed a new DVD writer.
But the 'add new hardware' box says it found a Printer, which I don't really have.

I don't know how to stop the window from appearing each time I startup the pc. if anyone has a suggestion, thanks very much.

Suggest you try this...

Open your Device Manager.
click on View ... Show hidden devices

Click on and Delete (with the Delete key) any devices that have a ? or ! in front of them.
If the Device Manager has an "Other" device category, open it and Delete any devices in the "Other" category.
Now, reboot.

The reboot will force Windows to refind the deleted devices and hopefully see them for what they are.
After rebooting, give Windows time to locate and properly install the deleted devices.

Go to the Device Manager and verify that all your devices are listed correctly.

thank you. it worked perfectly.
it's now one less annoyance at startup~ ^_^