Webmail; Draft couldn't be saved

[#1]

What would be reason Webmail keeps telling me a draft couln't be saved of a message?

[#2]

No reason I can think of assuming your Drafts folder is specified here:

[#3]

Next time it occurs I'll try & get a screenshot of red pop up box saying "Draft couldn't be saved" Bob.

[#4]

I get this frequently - it almost always happens after getting a "Can't send" message and I try alternatively to save it. Very annoying!