Opening up a page in a web browser ought to be a safe operation. Letting that page start a plugin, or running something it downloads, or flat out using IE for an unknown link, then I'd be more inclined to blame the user.<p>(This is why I use Foxit for PDF reading, I don't have a PDF plugin enabled in my browser, PDFs download to disk, and similarly QuickTime, RealPlayer, WMP etc. plugins are all disabled, with only Flash enabled but controlled via FlashBlock.)