So after resetting it today, I can't find the option to choose one to upload from my PC/Link. I can only choose the pre-defined ones...

I'm using Chrome by the way...

Here is the reason why...
http://forum.nihonomaru.com/images/rank/tags/20090220_kop6sB.gif
Unknown | Post 0-19 |
Avatar : No custom Avatar

You can find info like this in the link below.
http://forum.nihonomaru.com/newbies-guide/17842-member-ranks-avatar-size-tags-and-member-colors.html

Hmmm this is odd, before I had an Avatar though, I just wanted to change it recently...

I was able to upload an Avatar before even though i wasn't even at the 2nd Rank... hmm oh well thanks for the clarification.

It was a recent change made. So when you first joined the option was still available to you, but is now set to be unlocked after your 20th post.