PSE12 Error 16 when launching program

I have installed PSE12 - installation reported successful completion. I am running under Windows XP Home SP3. On 1st launch of the program, the Welcome screen appeared, but on selecting Editor it returned Error 16. I've tried uninstalling/reinstalling, but it won't even launch the Welcome screen now - it just returns Error 16 all the time. Initially I was installing on an external drive, but I have tried uninstalling and reinstalling on my C: drive, but get the same result.

I've tried the advice given at http://helpx.adobe.com/x-productkb/policy-pricing/configuration-error- cs5.html but:-

• Step 2 - I do not see the 'Use Simple File Sharing (Recommended)' option - so I've not been able to deselect it.
• Step 2 - The 'Show hidden files folders and drives' option actually appears as 'Show hidden files and folders' on my system - but I've selected this option.
• Step 3 - Under Properties for the SLStore folder, Read Only is ticked but greyed out. I can untick it, but after Apply/OK, if I view the Properties again it still shows a greyed out tick.
• Step 4 - For both Adobe PCD and SLStore folders, I am not seeing any Security tab, so am unable to set the permissions. It makes no difference whether I sign in to the Administrator account or the sole User Account (which I believe has administrative privileges anyway).

I would be grateful for any help in resolving this issue. [NB - I also have Lightroom installed].

Thanks,

Charlie