Many website problems can be resolved by clearing your web browser's cookies, cache and history.
While these can make your browsing experience more convenient, occasionally they can cause issues - for instance if a website changes but your browser shows you old information from the cache.
If a website isn't working properly clear your cookies & cache first (the browsing history doesn't often cause issues). If this doesn't resolve the problem try a different browser - some websites are designed to work best with a particular browser, and may only support the latest version of the browser. Remember that some websites can only be accessed from the University network - for these you either need to be on campus or using the Virtual Windows Desktop.