Update 2010-09-15: From one of the Snowstorm office hours meetings comes word that some releases of the viewers are not registering the Webkit, Quicktime, Flash, and other DLL’s correctly.I don’t have a fix.
Update:2014-06 – WebKit remains a problem. For the latest information scroll to the bottom of a WebKit article and look for the tag WebKit (or click this link). Click it to f ind the latest articles. You may need to use your browsers ‘Find-in-Page’ search (usually Ctrl-F) to find the pertinent part of the article. – Apple seems to have abandoned QTWebKit. In general the world is moving to Chrome Embedded Framework (CEF) as a better HTML5 type replacement.
Update: 2011-08-25 – Be sure you read the comments. Additional recent fixes have been added by others.
Update: 2010-07-23 – The new SL 2.1 viewer is causing people problems. It is an old error coming up again. There are several threads popping up on the SL forums. See: (Second Life WebKit Fail / Error – Problem Again) – One new solution is from Jesica (see comments), which is to find slplugin in the SL install folder, right-click for properties, and set it to Win95 compatibility mode.
Update: 2010-06-17 – With the release of Emerald Viewer version 2165 several people are running into this or a similar issue again. Those not having a problem installed to a new directory/folder rather installing over the top of the previous install. Others have copied the WebKit files from Snowglobe to fix the problem. Others just added slplugin to there anti-virus/firewall white list. In my version 2100 MOAP (Media On A Prim) isn’t working otherwise the viewer is fine. More to follow once I upgrade my viewer, watch for a 2165 review update.
A new problem with the Second Life 2.0 Beta Viewer and viewers based on the new viewer software. People are getting a popup error when starting the viewers. Some think it is the firewall, doesn’t seem to be. Somethink it is the anti-virus software, doesn’t seem to be. But, I have yet to find a solution.
Snowglobe users ran into this problem in October 2009… Its back…
The recent viewer update did not resolve the problem…
I added slplugin.exe to my Windows Firewall and told my anti-virus it is an exception. I checked my computer for older versions of slplugin.exe and replaced all the older versions with a copy of the latest. I rebooted the computer after the changes. After the restart the SL2.0 Beta viewer started without the error.