An error occurred inside the server which prevented it from fulfilling the request

I am getting the following error message: "An error occurred inside the server which prevented it from fulfilling the request." This happens when I search my email. It will not find any key word or name and my work depends on me being able to search client names and email addresses. Also, existing emails have a message "this message has no content" when I know this is not the case. The phone support has been no help, though I do have a 2 ticket numbers. But they seem to be unable to understand the issue. Even at the escalated level, they couldn't understand the actual sentence of the error message. I literally had to spell out words like "occured", "fulfilling" and "prevented". I have had the same comcast email address for 20 years. Please help. I use this email exclusively for work and I have already lost projects due to this issue.