Organisers of the London 2012 Olympic Games have suspended their re-sale of tickets due to the volume of demand.
A deluge of traffic on the Ticketmaster website caused the company's server to crash.
Members of the public had been trying to return their tickets for unwanted events.
The news comes after organisers revealed that 10,000 synchronised swimming tickets had been oversold.
Potential buyers have been told to keep checking the website for availability.
