tpc/ip

Resently I have notice a lot of computer running windows xp and they come to my job with the following problem.

Every time they try to log to the internet the received error stating the the tpc/ip can’t be found. This also happen to me last month, so what I did was restore my computer and it started to work again. What is causing this to happen and in the resent week it look like is happening more frequency.

Thank you in advance for your response