carpet is old, installed more than 10 year ago. thanks.

just checked, the two rooms with wood floor do not have this problem. so is it normal to have cracks in carpet flooring? how about the door frame cracks in the 2nd picture? same reason?

and the carpet floor is also making squeaky noise when step on it.

house was built in 1992. The black marks are not wear and tear, it was due to the iRobot bumping into baseboard and created marks.

To my eye, the door frame doesnt look like a crack. It looks more like who ever installed it, cut it too short and put a piece on it and probably a bit of filler and painted over it. Now the filler has separated and shows the line. Has your baseboard ever been taken off? and reinstalled. It looks very much like someone has had it off, and broken it in the process, and then reinstalled it with maybe a bit of filler there too, that has now dried out and shows the crack line. I see several places, where it was nailed and they seem to be quite random, like it has actually been off and reinstalled and new nail holes made at that time. Do you have a basement? or a crawl space? If so, have someone check the flooring and sub flooring from under the house, to see if there is any problems there.

another thought, is it just the paint which cracked?

It's not the paint. Those horizontal cracks are damage to the wood. It looks like it was damaged at some time, possibly by the carpet installers. It's also possible that some of the trim had cracks in it when installed and it got worse over time by being banged into.

There's separations between the top of the base board and the wall material; between the base board and the vertical opening trim, there's paint chipping on the base and wall; there holes and abrasions on the base board and wall trim.

Someone or something has beat up the trim and wall, over time, perhaps previous repairs, perhaps carpet installers. The damage is more than a Roomba.

My guess is that there's no connection between the floor squeaks and the beat-up trim and that these are issues based on the age of the house (1992) and how it's been treated since then.

just checked the basement which was finished by the previous owner 10 years ago, the baseboards over the carpet also have cracks. since I did not use Roomba in the basement, that rules out Roomba. Interestingly, only the rooms with Carpet have this issue, the rooms with wood or tile floor are fine.

the drywall above the baseboard are OK, that means it is not structure problem, right?

When carpet is installed. the carpet guys use a kick pad to stretch it over the nail strips around the edges of the room. It's entirely possible that they fractured the trim in various places when they were doing this.

Since it seems that only rooms with carpet have baseboard cracks, I'm raising another paw for careless carpet installers who cracked or broke the baseboards. It could very well be that the cracks or gaps were filled with spackling compound and painted over, and that has now cracked. I might try just re-spackling and painting. On a 1992 house, complete bb replacement would probably be better.

the cracks are all under the nail, as you can see from the 1st picture, almost at the bottom of the baseboard.

First and third images:

The carpet installer, in the parlor, with the knee kicker.

The humidity, or lack thereof, caused the baseboard to crack along the woodgrain because of the undue stress applied forcefully from the carpet

Second image:

The trim carpenter, in the bedroom, with the coping saw.

The atmospheric conditions cause the repaired door trim to separate (fail) at the repair joint across the woodgrain after years of iRobot abuse.

What do I win??

Sounds like the carpet installers are the prime suspects.

Spackle and repaint.

@Mark -- what you win is the approval from these fine folks.

The one wearing knee pads did it.

Could've been cracked during the initial carpet install and then painted over with paint spanning over the cracks. Movements from normal fluctuations in temp/humidity in conjuctions with bumping from the Roomba broke the paint "bridge" across the cracks making the cracks more visible/obvious.

I dont have a roomba, but, my son does. They use it regularly. Never once has it made a mark on their white trim. It is just as pristine as it always was. Several of my friends have roombas and pure white trim.None of them have marks like that on their trim either.I doubt very much whether anything on there is from a roomba.