I know it is an old threat, nevertheless it might help others to avoid switching to an other program/solution.

It likely is your anti-virus. Most AV programs handle IMAP different from the file-oriented pegasus client folders.

First test if you can see the messages when briefly switching off the AV. (close your browser first and only select messages from a reliable source). You can see them now (worked instantly for me after spending hours trying other things...).

Then switch back on your AV and figure out which exception should be set within your AV program.

I have installed Pegasus on a Windows 7 Netbook and set up IMAP connections to a user account on our Mercury server using both its external and internal IP address and tested the internal on using our internal wireless network and the external on uaing the wireless hot spot on my phone.

 Either version will connect to the target account and show the number of emails read and unread in all mailboxes including the IMAP inbox.  However is any folder is actually opened then the folder shows as empty after a dealy when the system is apparently trying to read the folder.  No error messages get displayed.  It is JUST possible that this user has his account open on a phone too also using IMAP, however having displayed his full folder list including the quantity of read and unread messages I would expect to be able to open a folder and see the actual emails therein.

Have you turned off any anti-virus from the Pegasus directories?

I use Pegasus IMAP to Mercury regularly and I don't experience the same problem - although I'm not using Win7.

Well we do not normally have anty problems and I can connectect to the account from my desktop and view the emails so it is something else...

I solved it in the end by putting Thunderbird on the notebook in question.  Still curious as to why Pegasus does not work with IMAP on that particular system.