gzclose() and gzwrite() error?

[basis]

Does anyone know what this error might be complaining about?

I think it occured when I was trying to download a package via the built-in package browser.

2: gzwrite(): supplied argument is not a valid stream resource
File: /home/ski/public_html/forums/Sources/Subs-Package.php
Line: 2108

The actual line at 2108 reads:

$fwrite($output, fread($fp, 16384));

hmm.. wonder could it be a write error??