For all its public devotion to innovation, the computer industry has been unwilling to break one rule -- it takes a keyboard and mouse to use a home computer.

But Hewlett-Packard is throwing that principle aside -- along with a few others -- in its new TouchSmart IQ770 desktop. This computer's screen responds to the touch of your finger.

This is an overdue development. Science fiction, from "Star Trek" to "Star Wars," has taught us to tap the screen of a computer to make things happen -- a lesson reinforced by the touch-sensitive screens we use daily at ATMs, gas pumps and airport check-in kiosks.

But the $1,800 TouchSmart doesn't just allow its users to do what comes naturally.

It also tries to replace the kitchen bulletin board, as well as the TV and stereo.

And its all-in-one design, thanks to its WiFi receiver and wireless keyboard and mouse, requires plugging in only one cable.

These other capabilities make the TouchSmart an extremely ambitious creation -- the latest in a series of occasional, often unsuccessful attempts to build a computer that doesn't look or act like a regular PC. Many firms have tried this, but only Apple has made a mass market out of it.

HP's worthy but unsuccessful experiment sinks for the usual reasons. It costs too much and runs too slowly. And its surface ease-of-use is not matched by the Windows Vista software underneath.

HP should have stopped with the touch screen.

Unlike the displays of tablet PC laptops, which require you to tap with a special stylus, the TouchSmart lets you use your fingertip.

Strictly speaking, you don't even have to touch this 19-inch LCD because it detects your finger from an eighth of an inch or so away. Even right-clicking works: Hover a fingertip over the screen for a moment, and the right-click menu will pop open.

The whole experience is oddly soothing, even if it does demand regular screen cleanings.

To show off this capability, HP added its own set of large-type software. You can check the time, look up a weather forecast, play some basic games, listen to music and view photos. You can also jot down notes (written onscreen, typed with the keyboard or recorded with a microphone) and save calendar appointments, then save them to your user account or put them under an account that anybody at home can view.

A SmartCenter screen offering quick access to these HP extras aims to be a computer-wide home page. The idea is that you'll put the TouchSmart in the family room or kitchen (though this 38-pound machine may be too bulky for that), and then the family can use it to stay in touch.

The SmartCenter programs go light on features, though. SmartCalendar, for instance, can't copy appointments to Microsoft Outlook or another personal information manager. Photosmart Touch can only crop and rotate photos and remove red-eye effects.

But all that could be forgiven if this software weren't so nightmarishly slow. Launching a program off the SmartCenter screen involved almost half a minute of the screen blinking on and off and displaying Vista's spinning-circle-of-boredom cursors. Music sometimes stopped playing while I switched applications.

Photosmart Touch couldn't even display previews of photos without redrawing them, one at a time.

This sluggishness would be irritating on an entry-level box. On a machine packing 2 gigabytes of memory and one of Advanced Micro Devices' fastest processors, it's inexplicable.

The TouchSmart's home-theater capabilities don't work much better. The computer ships with the right components -- it can burn CDs and DVDs, tune in to FM radio, and receive and record digital TV broadcasts with the help of a 320-gigabyte hard drive -- but not all these parts function as designed. The software wrapped around them often makes things worse.

That digital TV tuner, for example, had trouble staying locked into local stations' signals. The speakers sounded tinny and weak. Windows Vista's Media Center software crashed when I tried to burn a recorded TV show to DVD. And I couldn't use the FM radio: The Vista software kept saying I first had to set up the TV tuner, even though I already had.

Still other glitches undercut basic confidence in this system. The wireless keyboard sometimes acted like a manual typewriter in need of oil -- it would miss some keystrokes but register others twice. A system-maintenance screen told me to download an HP Health Check program, but it's still not ready a month after the TouchSmart shipped -- and won't be for another four weeks.

Not all of these things can be fixed immediately, but I thought HP could at least help get the FM tuner working. But a 40-minute phone call -- most of it spent waiting on hold -- ended with HP's rep asking me to pay $60 extra for a special 45-minute help session.

At this point, I realized what the next innovation in computer input ought to be: a computer that can recognize when its user has begun swearing at it, then respond by groveling for forgiveness.

Living with technology, or trying to? E-mail Rob Pegoraro at robp@washpost.com.