I'M sitting here surrounded by the telltale signs of computer disaster. Piles of manuals on the desk. A mound of diskettes. Notes from the technical-support departments of software companies. (I called three of them in the past week alone!)I embarked on this little adventure to make my computer run a little better. Right now, I'd just like it to run. Janet Driskill of Jeffersonville, Ind., writes: "In six years of computer operation only one thing has been constant. Nobody knows anything. The salesman who sold it to you? The so-called technical assistants? You get as many different answers to your questions as the persons you ask. Or the last resort, the instruction manual? Forget it." (I hear you, Janet. I'm staring at two red manuals that are worse than incomprehensible.) Janet's first computer didn't work because of a defective disk, which baffled the technicians. A printer she bought wouldn't operate because a salesman installed the paper incorrectly. Her computer mouse was inoperable for five years (five years!?) because the store personnel couldn't tell her she didn't have the necessary serial port. "I've learned by trial and error, mainly because I have the time and patience, and because when it works it is fascinating," she writes. "But it does seem that with all the expertise that goes into the production of these machines, some of it could be used to train adequate technicians and writers of their manuals." Even technical people are getting hung up by computer troubles. "I almost threw my computer out of the window earlier this week," declares Bob Janacek, technical director of a small New Jersey software firm. His system kept crashing while laying out a four-page brochure. What's going on here? Computers were supposed to make life easier. How did we fall into the complexity trap? Part of it is our own fault. We demand more of our systems. We want them to be simpler at the user level, which, ironically, makes them more complicated at the operations level. Take Microsoft's wildly popular Windows 3.0. It is far more intuitive than the older DOS operating system. Icons allow users to manipulate programs and move from one to the next much more easily. Yet it is vastly more complex and demands a lot of the hardware. I had to upgrade my computer - special software for the monitor and more memory for the machine - to get Windows to run well. As sophisticated software pushes the hardware harder and farther, the cracks in the system are starting to show up. Old machine A won't run the newest software B without special switch X, which conflicts with software C. Or maybe enhanced software C now runs on a new operating system but conflicts with software D when run on machine E. And so on. Throw a network into the equation, where various computers are linked, and the potential conflicts grow exponentially. It's getting hard for technical people (let alone computer salesmen) to keep up with all this. Standards help, of course, if computer companies could agree on them. But the industry lags in adopting them. Mr. Janacek suspects it's not the large company, which upgrades its equipment regularly, that will get left behind, but the home-user, who can't afford new equipment every few years. There are ways to avoid the complexity trap. Buy a computer from a reputable dealer who knows his systems and will help you when the chips are down. Stick with well-known brands of hardware. Be selective about software. "You have to have a Consumer Reports attitude on the software you buy," says Robert Keller, chairman of computer science at Harvey Mudd College in Claremont, Calif. He reads reviews and waits at least six months before buying a new software product, relying on friends and colleagues to try it first. (Professor Keller also recommends a Macintosh over an IBM-based PC, because the software conflicts are far fewer.) Now that I have Windows running, I wouldn't give it up for the world. But the investment of time and effort to get from there to here was large. That's worth considering before you wander into the software jungle.