I've got a client that sees the "Page can not be displayed" (nothing else) whenever they perform a certain action in their website. I don't get the error, ever. I've tried IE, FF, Chrome, and I do not see the error. The client sees the error on IE.
The error occurs when they press a form submit button that has only hidden fields.
I'm thinking this could be some kind of anti-malware / virus issue. has anyone ever dealt with this issue?
It would be useful to you to figure out which error code is returned. Is it 404 - Resource not found or 503 - Forbidden Access? There are a few more, but in any case, it would help you figure out the cause of the problem.
If your client is running IE, ask him to disable friendly error messages in the advanced options.
Check their "hosts file". The location of this file is different for XP and vista
in XP I believe it's C:\windows\hosts or C:\windows\system32\hosts
Look for any suspicious domains.. Generally speaking, there should only be ~2 definitions (besides comments) in the files defining localhost and other local ip definitions. If there's anything else, make sure it's supposed to be there.
Otherwise, maybe the site's just having issues? Also, AFAIK, FF never displays "Page cannot be displayed", so are you sure this is the case in all browsers?
In IE, go to the "Anvanced" section of "Internet Options" and uncheck "Show friendly HTTP errors". This should give you the real error.
Is this an IE message? Ask them to switch off "short error messages" (or whatever they are called in the english version) somewhere deep in IEs options - This will make IE display the error message your server is sending instead of its own unhelpful message.
Also I've heard that IE might be forced to show server provided error messages if only the page is long/large enough, so you might want to add a longer " " section to error messages. This information is old enough that it might have effected older versions of IE - I usually get to the root of problems with eliminating the "short error messages"
Note: I'm neither running IE nor Windows, therefor can only operate on memory regarding the name of the config options of IE6...
Update: corrected usage in the suggestion to provide longer error messages... Perhaps somebody with access to IE can approve if longer error pages still force IE to display the original error page instead of the user friendly (sic) one.
You can try using ieHTTPHeaders to see what is going on behind the scenes.
Do you have any events applied to your submit button? Are you doing a custom submit button that is a hyperlink with an href like "javascript:void(0)" and an event attached that submits the form?