Hi Steort,
Welcome to Apple Support Communities!
The article linked below provides a lot of great suggestions that should be able to resolve the issue.
iCloud: Troubleshooting web browser issues with iCloud.com
http://support.apple.com/kb/ts4050
Symptoms
When using iCloud.com, you may experience issues such as a web page not loading, or the web browser displaying distorted or outdated content. Learn more about troubleshooting these types of issues.
Resolution
Use a supported web browser
For the best web experience with iCloud.com, make sure you're using a supported web browser. For more information about iCloud system requirements, see this article.
Enable cookies and JavaScript
Cookies and JavaScript need to be enabled in order to properly access iCloud web services. If you're not sure whether you have Cookies or Javascript enabled, visit iCloud.com. If you're missing either Cookies or JavaScript support, iCloud web pages will provide an alert. If you're unclear on how to enable Cookies or JavaScript, refer to the Help menu for your browser.
Troubleshooting the cache
Most web browsers use a feature called "caching" to display frequently used information, images, and web resources. Caching stores or "caches" this information on your computer, so your computer doesn't have to download the same information every time it visits the same webpage. Caching makes subsequent visits to the same website or webpage faster.
If a website or webpage has been updated since your last visit, your browser sees the update and then loads the new content instead of the old cached content. In some cases, this doesn't work as expected and your browser displays the old information instead.
Follow the instructions below for clearing your web browser's cache in Safari, Firefox, and Google Chrome on a Mac; or Firefox, Internet Explorer, and Google Chrome on a Windows PC.
To clear Safari's cache on a Mac (Safari 6.0 and later)
- Close any open Safari windows.
- Choose Safari > Preferences > Advanced.
- Select the checkbox labeled "Show Develop menu in menu bar".
- Close the Advanced window.
- From the Safari menu bar, choose Develop > Empty Caches.
-Jason