Bug:
Blank screen with the only HTML coming from the server being '<!-- SHTML Wrapper - 500 Server Error -->'. Both frontend and backend, and all pages on them, display nothing.
Here's what I did. I was trying to put up a ZIP folder as a downloadable product:
Created a new media item in the Media menu, gave it a unique name, set it for 'for sale', entered the files location on the server, selected 'Replace Thumbnail', browsed to an image on my machine, hit Save.
Here's a few errors from my server log that appear when I try to access my site after the bug:
[Thu Feb 16 23:41:10 2012] [error] [client 174.***.***.***] SoftException in Application.cpp:601: Directory "/home2/account/public_html/siteroot" is writeable by group
[Thu Feb 16 23:41:10 2012] [error] [client 174.***.***.***] Premature end of script headers: index.php
[Thu Feb 16 23:41:10 2012] [error] [client 174.***.***.***] Premature end of script headers: 500.php
[16-Feb-2012 23:28:30] PHP Warning: Missing argument 2 for VirtueMartModelMedia::store(), called in ***/administrator/components/com_virtuemart/controllers/media.php on line 76 and defined in ***/administrator/components/com_virtuemart/models/media.php on line 337
The only way to fix it (that I found) was to reinstall Joomla. I reproduced this twice.
UPDATE: I managed to reproduce this a few more time and I also found a way to bypass it. If I first just upload the product image, set it as 'for sale', then save, I can then go back and point its URL to the ZIP folder. Kind of a roundabout way, but at least it doesn't destroy the site.