Here's the thing: when a hosting provider hosts a web, not everything is saved into the same computer. Images can be scattered around many computers and even your admin area could be somewhere different. When everything works fine, you don't notice, but if one of the computers fails, then you would experience that some images are not loading or that you can't temporarily access you admin panel.
If it worked ok, you haven't changed anything, and then somethings fail, it can be due to changes you are not aware of at your hosting.
Other safety things to rule out possibilities would be:
- deactivate all plugins one by one, to see which one causes the problems (if so).
- return to the basic Twenty Eleven theme and see if the problems persist...
- and finally, if problems are still there, contact your hosting.
I know that is tedious, so contact your hosting to rule out that first.