Not long ago, we bought an HP Color LaserJet 2605dn printer for our home office. Our experience with this printer has been absolutely fantastic, with one exception. If the printer had been sitting inactive for a while, and you send it a print job the printer would make this horrible squealing noise while printing the first page.
I was so baffled by what was causing this noise that I ended up calling HP about it. Their recommendation was that this was very unlikely, and that I should return it to the vendor for an exchange. I did this, and you can imagine my surprise when the new printer exhibited exactly the same behaviour.
After looking around the support forums and finding nothing, I thought that maybe this was some sort of a warning indicator noise. All at once, it hit me... It must be a power warning. This made sense, as all my peripherals were plugged into the same surge protector.
Eagerly, I moved the printer into its own outlet and sent a print job. There was no squealing. In fact, there has been no squealing from the printer for the past 3 or 4 weeks since I stumbled on this.
Now, this printer is absolutely perfect. I wouldn't hesitate to recommend this printer to anyone that is looking for a high powered, network-ready color laser printer.