Dig through the menu's for an option to set the volume for that beep (or off). I think I had to turn mine down too.

One thing that I HIGHLY recommend is switching from the "DirecTV style" guide to the Tivo one. I had DirecTV for over a year prior, but I fell in love with the Tivo Guide in minutes AND it draws WAY faster. To change, hit GUIDE then INFO and select "Tivo style".... this is from memory, so I may be off a bit... it might take a day for you to get a full guide too...