Newcastle University has been hit by a cyber attack which is expected to take "a number of weeks" to sort out.
It comes after a recent hack on Northumbria University, which affected exams and its clearing hotline.
The issue has been reported to the Information Commissioner's Office and police after the IT problem came to light a week ago.
Newcastle University apologised to students and staff for the "ongoing" disruption.
It added it was continuing to take measures to secure its IT services.
New students are due to begin term on 28 September, with existing students returning after that.
Services not operating
The university said its teams were working with a number of agencies, including police, to find out what happened.
"We take the security of our systems extremely seriously and we were able to respond quickly to this situation," a spokesperson said.
"The nature of the problem means this is an ongoing situation which we anticipate will take a number of weeks to address.
"A number of our IT services are not operating and will remain that way for the duration."
The university updated its advice to staff and students on its website on Friday.
It says people can still access limited services, including email, office applications and video conferencing tools.