I don't know it is falsepositive or something wrong with amember.com. But amember.com is being blocked by malwarebytes. it says amember.com is a malicious site. Actually the ip is being blocked:
Every site on the web can become of victim of XSS. Amember is in good standing according to Google: http://www.google.com/safebrowsing/diagnostic?site=amember.com However (according to Google), the hosting site it uses has been attacked before (like many others, including my own) - which is why your program is probably warning you it's a "potential". AV programs do that to protect themselves. I highly doubt aMember is injecting malware, especially on purpose. I also don't believe everything an anti-virus tells me. I have a 100% virus free .exe file I created myself, so I know it's totally clean, yet Norton warns it may have a trojan inside LOL. I guess it's good to bring it up though, so at least the web owners know.