Desiree still seemed to have some kind of subtle problem.

But subtle problems can take hours for a technician to find.

This has been a frequent and subtle moral problem in the intellectual life of the last hundred years.

He wasn't talking about any subtle problem: burden of responsibility or anything.

"We've got to learn to find and attack the subtle problems," he said.

In fact by abstracting the subtle problems involved they can actually make things worse.

But that doesn't protect them from more subtle problems.

Perhaps it was now giving him more subtle psychological problems?

However, this technique has many subtle problems and should usually be avoided.

Even with more conventional subject matter, judging what will interest children is a subtle problem.