Sending Black messages in Win 8

Since upgrading from Win 7 to Win 8, my eM Client has started to randomly send messages with a black back-ground and black type, making my message unreadable by the recipients. I have looked at your web support for any clues, found another person had similar problems that were solved by changing or altering the signature. I tried this but to no avail. Then I spotted a notice advising that beta eM Client 5 beta is available for download. This I did in the hope that my problem was due to some incompatibility with Win 8, unfortunately this was not the solution, as I am still sending “black” messages.
Your help would be much appreciated, as I like your software and would be unhappy if I had to give it up for something else.

Best regards

Is this your case?…