I should add that Lightroom 4.3 can open the RAW files on the same machine that PSE 11 fails.
This is what I can do with the following raw files
Sony ILCE 6000 .ARW Convert to DNG - can not open them at all (FastStone Image Viewer can display these)
Lumix LF1 .RW2 Can open on all systems + Lightroom
Nikon D300 .NEF Can open on all systems + Lightroom
Nikon D300s .NEF Can open on all systems + Lightroom
Nikon P6000 .NRW Can open on all system + Lightroom
Nikon 1 V2 .NEF Can open on all systems + Lightroom
In short, PSE 11 on my PC workstation Win 7 will not open any RAW file. I suspect that the fault lies in system files (e.g. add-in & DLLs) and/or the system registry. PSE 11 reports that all add-ins and its own components are up-to-date.
FastStone is just showing you the camera-embedded preview JPG not decoding the raw files so can do that for newer cameras without any sort of update.
The A6000 needs ACR 8.4/LR 5.4 or newer.
The LF1 needs ACR 8.1/LR 5.1 or newer.
The D300 needs ACR 4.3/LR 1.3.1 or newer.
The D300s needs ACR 5.5/LR 2.5 or newer.
The P6000 needs ACR 4.6/LR 2.1 or newer.
The Nikon 1 V2 needs ACR 7.3/LR 4.3 or newer.
LR 4.3 has the same camera-support as ACR 7.3.
PSE11 ships with ACR 7.4 which can be updated to ACR 8.0.
What ACR version does PSE11 report, if any, if you do Help / About Plug-ins / Camera Raw in the PSE Editor?
If no version is reported, then reinstall PSE11.
What is the URL for ACR 8.4 plug-in for PSE11?
I can find info on camera support, Adobe product compatibility, DNG converter and a whole host of useful information that is not ACR 8.4 plug-in for PSE11.