I've uninstalled dopus 10.5.5 and pdfxchange viewer v2.5.207 (I think) and installed dopus 10.5.6 and pdfxchange viewer v2.5.214.2.
I'm using the same setup/config but now if I click on a pdf file I get a window pop up asking me if I want to open or save it (see pic below), which is quite irritating.
I just want the pdf to display in the viewer pane like it used to. I've solved this problem once before but I can't remember how. 
Please go to Preferences / Viewer / Viewer Plugins, select the ActiveX + Preview + Office + Web plugin, and click Configure.
A window with a list will open. At the top of the list will be a Preview Handler section.
Is there a line for the PDF-XChange there? If not, try reinstalling PDF-XChange.
If there is a line, check that it has the .pdf extension assigned to it.
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.
thanks for the quick reply btw 
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.)
It works in the 32 bit version of DOpus but not in the 64 bit version.
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.
What happens in Windows Explorer?
It just shows the icon in the bottom left hand corner. I can't check the 32 bit machine right now but I'm guessing that one will display a little picture of the actual pdf.
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.)
Am having a similar problem in Opus. As usual I would like to use pdf exchange viewer to view pdfs in Opus. PDF does display but I can no longer see the pdf exchange tool bar
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.
my error on the xml not showing. I had it open in word and once I closed it, the xml showed in opus.
Am still not able to see the pdf exchange toolbar in viewer.
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.)
pdf exchange is next to the file name in the viewer window in Opus
"ActiveX + Preview + Office + Web" viewer plugin's configuration window has pdf exchange assigned to .PDF
Adobe PDF for Vista and Nitro PDF are unchecked
Although I usually use chrome as a browser, I opened a pdf in IE and the pdf exchange toolbars show just fine.
In the plugin config, turn off the PDF-XChange preview handler, and add .pdf to the Internet Explorer 32-bit line.
I tried that and it at least gives me the two page view of Adobe Pro but then I no longer have access to the pdf exchange toolbar
Ok, am now setting it up with Adobe 11 toolbars in Opus. Just out of interest, does pdf exchange no longer work with Opus?
thanks for your help.
You should get the same as in IE if you're viewing the file via IE in Opus. Is that not happening?
PDF exchange toolbars show up in IE but not in Opus 11 when I have pdf exchange checked in the ActiveX + Preview + Office + Web" viewer plugin's configuration window
No, in your case you don't want to check PDF-XChange's preview handler, as it is probably different and more cut down than the separate PDF-XChange Internet Explorer plugin*.
If you want the same in Opus as you get in IE, set the plugin to use IE for .pdf files and turn any PDF preview handlers off.
(*Why they are so different, you'd have to ask the authors.)