[plt-scheme] Planet HTTP 403 errors

Hi all,

I seem to consistently be unable to download planet packages from my  
home computer: I get a 403 error, regardless of package.  Since I'm  
usually working from school (and for a long time I only happened on  
this error at odd hours of the night on weekends, which let me assume  
it was a periodic planned-downtime issue) I haven't bothered to report  
this, but it's been consistent for the last few weeks, happening every  
time I've tried regardless of time of day.

I have an off-the-shelf D-Link router / masquerading firewall, and am  
running OS 10 Leopard.  Logging into a server on my university  
account, I can download packages with no problems, but at home  
(require (planet ...)) always fails, showing the error:

require: PLaneT could not download the requested package: Internal  
error (unknown HTTP response code 403)

I've tried multiple versions of DrScheme and mzscheme.  Any ideas, or  
suggestions for further troubleshooting?

Thanks,
jmj