Spelling Check is not Working on Eudora Mail Client

So far I have used two mail clients. One is Outlook Express and another one is Eudora which I am currently using. Previously, I was using Outlook Express and due to face some technical errors I transferred into Eudora. I think that Eudora is a strong and secured mail client and enjoying great service.
But the spelling check option is not working from this morning. The spell check option is still there in the tools menu. As a part of try I do uninstall the program and reinstall it again. I get back the spell check error option and it was also working but only for one hour. After 1 hour of normal service, it vanished again.
Please help me.
