Looks like the Great Firewall or something like it is preventing you from completely loading www.skritter.com because it is hosted on Google App Engine, which is periodically blocked. Try instead our mirror:
This might also be caused by an internet filter, such as SafeEyes. If you have such a filter installed, try adding appspot.com to the list of allowed domains.
You can also check the App Engine system status pages for Python apps, but they are not very reliable. We are hosted on Google App Engine, so if Skritter is going slowly or having serving problems, then the Google App Engine team has probably been paged and is working to restore performance.
If you are unable to access Skritter well enough to do your study, either due to Skritter server problems or connectivity problems on your end, let us know and we'll add extra time to your subscription, to help make up for the lost time. Sorry for the frustrations!