It happens to some websites that AT's forum software blocks some websites from linking. Take ChiefValue. While you can write
www.chiefvalue.com out, try linking it using the linking button. Then look at what happens when you post it......the chiefvalue part gets starred out.
I thought his links were to ChiefValue, but when you replace the stars with CV, it comes up as page not found, so it's not CV this time that's getting blocked.