When I open certain sites in Firefox (e.g. www.halifax-online.co.uk) i immediately get a popup from http://www.consumersurveygroup.org asking me to fill in a survey. This survey appears to link to the site I am accessing
The unusual thing is that, although I do not use Internet Explorer the invitation always opens in Internet Explorer.
More than likely something like Malware on your PC, considering that pop-up isn't opening in Firefox, but rather it is opening IE. I suggest doing a thorough Malware scan.
Install, update, and run these programs in this order. (Not all programs detect the same Malware.) They are all free for personal use, but some have limited functionality in the "free mode" - but those are features you really don't need to find and remove the problem that you have. Note: If your Malware infection is bad enough and you are mis-directed to URL's other than what is posted, you may have to use a different PC to download these programs and use a USB stick to transfer them to the afflicted PC.