I have a site with a PR 4 that is clearly sandboxed by google. The PR was gotten before the sandbox occured, but still holds
There are two types of PR and both squat to do with the sandbox Toolbar PR that little green thing Actual PR measured constantly by G Sandbox is a time factor You will not rank highly for short competitve keywords for about 12 months. And A 5 year old site tends to rank higher if all other factors are the same than an unsandboxed 1 year old. Best thing u guys can do is go to the domain name thread and buy another domain, or get jobs for the next 12 months
We've had PR increase from 3 to 4 very recently and it feels like we're in a sandbox (no in any SERPs for our competitive keyword).