in my frustration last night, and after trying everything people have suggested on this site, i simply reset LimeWire settings to default and it's working fine now. I think what happened was I installed LimeWire before MSAntiSpyware so didn't give it the chance to prompt me to allow or block LimeWire.
After writing this post I'll check for an update to MSAntiSpyware, I assume you mean a software update as I have the most up-to-date definitions.
Thanks for your help LOTR