Most problems with sites not loading correctly can be resolved by clearing your 'temporary internet files' or 'cache' and making sure you have the latest browsers installed.
If you are already up to date, sometimes reinstalling them can will also fix any minor issues.
You may also want to look to see if you have recently installed any new software that may be interfering with your browser, especially any anti-virus or anti-adware software. If you do, try uninstalling or disabling the software (it can be switched back on later) and try visiting your site again.
Having the latest version of Adobe's Flash Player also helps. Again, if you do already have the latest version, try reinstalling.