yes PDF-XChange is in the preview handlers but without any extension. I added .pdf in there but it made no difference. I also tried deleting .pdf from the internet explorer bit (under web browser). I'm not sure whether I deleted .pdf from the active X section as well but I ended up with pdf files displaying as text. that's when I gave up and restored my dopus settings.
I did, however, manage to solve the problem. when installing PDF-XChange Viewer you need to have the browser plugins selected and also have 'Display in browser' selected at the end.
Sounds like the PDF-XChange preview handler (or its installation / registration) may be broken. Presumably it doesn't work in the Windows Explorer viewer either in that case.
Not too important though, as long as you have something that works via the alternative browser plugin. (Although it can be safer to avoid the browser plugin and use the preview handler, so that you're less likely to view a malicious PDF file while browsing the web. OTOH if you don't use IE as your primary web browser then it's not much of an issue either way.)
PDF-XChange must have its registry settings or 64-bit version messed up in that case, since 64-bit Opus will happily use 32-bit preview handlers if they are what has been assigned to the extension, unless a 64-bit version of the same handler is also registered.
If the viewer isn't working in Explorer either then it's definitely a problem with the viewer. If reinstalling PDF-XChange doesn't help, I would ask for support from the people who make it. (Since it affects Explorer, you don't need to mention Opus at all. If they can fix it in Explorer, it should also be fixed in Opus.)
Havenow upgraded to opus 11 to see if that would fix the problem. No luck. Also now have the problem that xml files no longer show in viewer - just (Shell Icon) in the file name. That used to work in opus 9.
Which PDF viewer is being used at the moment? (It should say next to the filename in the viewer's titlebar.)
What does the "ActiveX + Preview + Office + Web" viewer plugin's configuration window have .PDF assigned to? (See first reply in this thread for how to open the configuration window.) (There may be more than one line with .PDF assigned to it, in the different sections of the list.)