Hi emma, follow this link to microsoft and see if their tutorial can help you with the problem at all:
You cannot log in to or connect to secured Web sites in Internet Explorer
If not, that is okay, I can take you through a couple steps that may solve the problem. This is the picture you sent me, just wanted to post it again. If you click these pictures, they get larger (you can click them up to 3 times):
First, have you ever logged in to this website before, and did you have any trouble with this pop up then?
Next, try disabling some add-ons just in case one of them is causing this problem. As in the picture, only have these add-ons enabled, and disable all other add-ons. Go to "Tools" > Manage add-ons":
If the problem persists, go in to "Internet Options" by clicking "Tools" > "Internet options". Click the "security" tab, and find the button towards the bottom right of the window that says "Default level" and click it, if it lets you. Then go to the "Privacy" tab and click "Default" towards the middle on the right hand side, if it lets you.
If the problem continues, type "Internet Explorer (No Add-ons)" into the start search bar and click the program of the same name. Check the website again to see if you get the error. If you do, exit all internet web browsers and go to the start search bar again - type "Disk Cleanup". If it asks you which drive, select ( C: ), or your main drive. Check only the boxes of "Temporary Internet Files" and "Offline webpages" (unchecking any other pre-checked boxes), and click "OK". It will look like this:
Let me know if you still get the problem, I have some more tricks up my sleeve.
If you are using Internet Explorer 8, I would recommend installing and using the newest IE9. Its look is a little different and may take some getting used to, but newer means safer and more compatible, at times. Here is the website to download it if you would like to:
http://windows.microsoft.com/en-US/internet-explorer/products/ie/home