Sounds like you have some settling going on, which is not uncommon. Any active crack, even a minor one, is not going to stay closed with a simple spackling. Using tape is the only thing that has worked for me. Of course, you will have to feather the patches out over a larger area so you don't have obvious humps. And, if you have a textured wall, that will mean re-texturing to match. It can be a moderate amount of work, but may be the only thing that will be a permanent fix.

If the cracks are not wide,just hairline cracks, try culking them with latex caulk and paint.

There is only one permanent solution, and that is to remove some of the drywall and reconfigure it so there is no joint at the corners. In cold weather climates, joints at corners will always crack, guaranteed. Go to the link below for details on how to fix this for good.

Here is a link that might be useful: Fixing Drywall Cracks at Window Corners

The house is 18 years old so it certainly could have settled.

Yes, the cracks are really fine but I thought I read somewhere recently that you shouldn't put caulk in nails holes, etc. Are thin cracks exempt from that?

We live in the south and I'm pretty sure that at least some of these cracks are not at joints. I think I may have pictures during the construction phase so I'll see. LOL..If the answer is to replace the corners, I think I might learn to live with the cracks! I'm the only one that notices anyway. ;-)

If they are really fine cracks, go with the paintable caulk I've done it with fine cracks before with no problems. saves a lot of time and mess. The caulk will flex with the seasonal changes in framing. Just so as long as the cracks are very narrow.

mdod-
Since the cracks have been previously patched and are now re-opened, I'm still of the opinion that taping is more likely to work better than just caulking.

I'm in So. Ca. & after 2 different quakes had to repair. We found that bathroom caulk worked just fine I just went looking in hall for where cracks were, can't find the 1 the other was longer so shows slightly if you look just right it goes from bathroom door to about 4 in. from the end of wall where the hall makes a turn. It's been since 1993!

Caulk the cracks. Repairing drywall with drywal joint tape and setting compound is an art form. go the easy way and caulk them. I doubt very much they will reopen

I have a similar problem only the hairline cracks appear at taped joint on the ceiling! In the past, I have dug out the joints, re-taped with fiberglass mesh tape, and re-mudded, finished and repainted. Within a year and a half, identical cracks are back. In the center of the crack, there is a small amount of compound that has heaved slightly above the surface.

In addition to the above attempted solution, I have tried Rock Hard Water Putty, that spray rubber that one paints over. None have worked.

I am ready to try the caulk. Think it will work?

Obviously some regular seasonal movement is going on.

Will the painter's caulk work?