I have four boxes which have popped up showing this error with wah.
The boxes have an OK button but neither pressing it or clicking the close box gets rid of it.

What should I do?

From memory there is not much you can do apart from abort them. Are they all from the same batch? If so, I will get a message to Andy or Sarah at the project on Tuesday, Monday being a public holiday here in UK.

With your computers hidden, we'll need more info. At the least, the batch number.

Generally, that error means that the model didn't like something about your computer.