Until you figure it out, set your bookmark for this website to that page (it will force you to log in first if you have your settings to clear history on closing).
Which now has me thinking....
Might be something updates with your internet program. Unlikely, but possible.
Try doing a little house cleaning.
Internet options/clear history, cookies, temp files/folders.
Start/Run/%temp%...
In the window that opens with all the files, right click once anywhere in the file list (right pane)/Ctrl+A/delete. There will be one or two files/folders that can not be deleted. Rinse and repeat after clicking OK a couple more times. You will want to save and close all open files/programs before doing this.
Start/search for "Disc Cleanup" and run that. DO NOT SELECT the system restore points.
May as well run a defragment while you are at it. Won't help the current problem, but if you don't have it done on a fairly regular basis, it's good maintenance.