I don't know if anyone else can replicate this, but I have found the browser Opera to have an interesting quirk.
A couple of days a go I was adding a record to my blog http://www.localspider.co.uk and after adding something in on the manual excerpt field, when I hit Publish, the screen refreshed and the field was empty, tried it again and when update was hit the same thing happened. The weird thing is that it did not seem to affect any other field.
I spoke to technical support for my hosting and after about an hour looking at permissions etc, the problem still seemed to be there.
As a attempt to try anything, I then used Firefox instead of Opera to re do the manual excerpt and it worked.
I dont pretend to understand whats going on as on the database its a text field like other fields in the table, but for some reason Opera seems to cause the issue.
Really weird and strange, as life is to precious Im not worried about a reason or fix, Im just going to use firefox from now on.....