User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:9.0.1) Gecko/20111221 SeaMonkey/2.6.1 Build ID: 20111221001913 Steps to reproduce: I had several browser-windows of Seamonkey open at that time. One was http://www.facebook.com/bicycledate.de. I clicked on the link http://www.bicycledate.com/ in the text inside this site. I use Win7x64 with Seamonkey 2.6.1. Actual results: The system freezed immediately. No mouse an keyboard inputs were accepted anymore. I had to use the power-off button. The problem can be reproduced on my machine Dell Latitude E6410. I didn't try this on other systems.
Not a SeaMonkey issue, its related to your system, possibly graphics card driver. I suggest updating your system and drivers, and contacting dell if the problem persists.