From some testing, I basically just kept chopping bits off of the long URL above to see when it 'breaks'.
The original URL is:
http://www.liveandshop.com/index.php?
option=com_jfbconnect&controller=social&task=likeCreate&
href=http%253A%2F%2Fwww.liveandshop.com%2Findex.php%253Foption%253Dcom_k2%2526view%253Ditem%2526id%253D118%253Atest
I broke that into multiple lines because in my post above, you may not see the full thing in your browser.
If I remove it down to the below, where I remove most of the referring URL, it still breaks:
http://www.liveandshop.com/index.php?
option=com_jfbconnect&controller=social&task=likeCreate&href=http%253A%2F%2F
However, if I simply remove the encoding for the :// part, it works (you'll see just a blank page, but that's a good thing:
http://www.liveandshop.com/index.php?
option=com_jfbconnect&controller=social&task=likeCreate&href=http
So, it seems something with your server is seeing the http:// in a URL and not liking it. We encode the URL (which is why you see the %253A%2F.. stuff. Encoding should make it so your server ignores those types of characters. However, again, if you have a firewall or other security mechanism on the system that's very agressive, it may try to decode and prevent even encoded query string parameters from working.
Hope that gives you some more information about where to look, or at least what information to provide to your server/hosting techs.
Alex