The 'session suspended' message you are seeing occurs either when a large amount of content is being downloaded (particularly in a systematic manner) or when the file being downloaded is extremely large.

NUIT have limits in place to prevent excessive downloading of content to ensure that the university operates within the licence terms and conditions agreed with the resource provider.

It may be possible to dismiss the suspension by clearing your web cache and cookies or trying a different browser, however your access should be automatically reinstated once the 2 hours has expired.