The problem seems to be server side, not client side... don't worry—you are safe.
I see that the site is referencing links to hard-code IP addresses (e.g. 144.22.31.223) rather than 'soft and friendly' URLs (e.g. talkmagic.co.uk)
The problem has been going on for a couple of days at least, but the forum DOES still function correctly.
Although when logging in you get a 'page not found' message, immediately go back to Talkmagic.co.uk homepage (type in the URL in your address bar) and it should function as normal (i.e. you will be logged in)
These 'glitches' usually resolve themselves (with the help of a gentle cyber-nudge from our esteemed host

)