mmm -- I could be wrong of course, but I don't think there will be many PSCS3 users on this board. In which case I think you'll get a quicker and more knowledgeable response from the official Photoshop user's forum here Hells: http://www.adobeforums.com/cgi-bin/webx/.ee6b366/
You'll need to register to post (the norm as you no doubt already know) or you may care to peruse existing threads which may cover your problem before doing so. I do hope you get it resolved, and soon.
Strangely though, the file 'icmp.dll' is a Windows file essential for networking (internet control message protocol) so quite why PSCS3 should trigger the error is intriguing -- perhaps it's required by PS for checkng your activation status (as well as program updates), but I would have thought any problem with an essential networking/internet file such as that would prevent you having internet access altogether -- which I assume hasn't happened. Hope that forum can shed some light.