Customer is not able to sign in to our intranet

[Tom]

We had a customer continued to be unable to access our
intranet even though given new passwords twice.

Is there some sort of setting on the customer's computer
which could cause this situation. The customer was able
to sign in using a username and password regularly in the
past. This problem cropped up about a week ago. Our IT
people have give this person a new temporary password
twice since the problem with access started about a week
ago.

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