As some of you may or may not know, a little while ago the forum threw a bit of a wobbler. One of the lasting problems associated with this seems to be that anyone who tried to access the website during that time now has issues logging into the website, since this still seems to be affecting a lot of people, here are a number of solutions;
Actual solution:
i) clear the temporary internet files and cached files from your computer, the exact method to do this varies depending on your browser, have a look here to find out how to do this in your browser.
Temporary solutions:
i) using a different computer should work
ii) using a different browser on the same computer should also work
If anyone is still having problems let me know and I'll look into it