Two year old site drop PR from 3 to 0

[PowerUp]

Hi, I have a website.
Today, I found out that my site of about two years with PR3 has dropped to PR0 (white bar, not grey bar).

Funny thing is, in my Google Webmaster Tools, I can see that 95% of my pages have low PR, with my homepage having the highest PR. So... my question is, if my highest PR page is a "low PR", why is it showing 0/10 PR in the Google Pagerank toolbar?

[JohnRoy]

The pr toolbar is NOT accurate.

It's wise to have PR distributed across all pages; route inbound links to inside pages (aka deep linking) and not only the home page.