I agree with Eric it would be a good idea to link to your root domain and not the specific file. You can just link to yourdomain.com or build your links to your homepage using code similar to the following: Home.
I have also seen instances where yourdomain.com and www.yourdomain.com are treated as separate pages and cause similar problems. It appears you are using www.yourdomain.com so while you are messing with 301 redirects you might want to add one from yourdomain.com to www.yourdomain.com for all URLs in case a link is made to yourdomain.com.
