Q: When the temperature is very cold, my garage door opens about a foot and then stops. If I disconnect the automatic opener, I can open the door manually without a problem. If I reconnect the opener, the door opens normally. Do you have any ideas about the cause of the problem and any possible solutions?

A: The cold is probably to blame. When this happened a few years ago with my garage door, I lubricated the drive in the middle — where the emergency release is attached — and it fixed the problem. I think the original lubricant on the screw drive either wore off or got thicker because of the colder temperatures. I sprayed WD-40 on the screw drive, and the door opened just fine. Your problem might not be exactly like mine, but my solution is worth a try.

Q: Within six months of moving into my home, I was diagnosed with asthma and eventually developed a sinus infection that recurred for 10 months. When a friend broke her leg in September, I spent four nights a week helping her; after a couple of weeks there, my sinus infection cleared up, and I felt better than I had in years.

But within a week of returning to my home, the symptoms had returned. I contacted a lab to take air samples in the basement and my bedroom. The basement had very high levels of mold. I had a lab remove the mold, and the basement does seem much better. However, I am still having problems, mainly with my breathing. I do not know what to test for next or whom to contact.

When I bought the house, there had been a home inspection two months prior by another buyer. That deal fell through. My Realtor suggested that we use that inspection rather than pay for another. There was no air-quality testing done. So far, I'm out $4,500 and still can't live in my house. What can I do next?

A: Home inspections are usually money well spent; it's unfortunate the real estate agent talked you out of one. Buyers should attend the inspection, ask questions, raise issues, discuss the report — in short, find out everything possible about the condition of the house.

That said, the typical home inspection would not have included an air-quality test. If the home inspector had detected a musty odor, he or she would have recommended that you hire a testing firm. Once mold is discovered, cleaning it up is wise. But if you don't address the cause, simply removing the contamination won't solve the problem — the mold might come right back. Did your lab pinpoint the cause?

The best basement-mold-elimination job I've ever seen also was the most expensive and extensive. Everything was ripped out, and the floor was plugged up. After the walls were power-washed, they were covered with coats of waterproofing and then painted with a nontoxic white paint.

According to government researchers, reaction to indoor air pollutants depends on several factors, among them age and pre-existing medical conditions. In other cases, whether someone reacts to a pollutant depends on individual sensitivity, which varies tremendously. Some people become sensitized to biological and chemical pollutants after repeated exposures. Other health effects show up years after exposure, or only after long or repeated exposure.

In addition to mold spores, health problems have been traced to excessive moisture in walls, carbon monoxide from fireplaces and faulty furnaces, and products that are used to kill pests.

Your house should be more thoroughly examined. I suggest contacting the local chapter of the American Lung Association, which will be able to provide you with information about the causes of indoor air pollution and what can be done. That group, or your state Department of Environmental Protection, might be able to provide you with names of reliable testing firms.