currently our database uses quite a feq guid's with a default value of newid(), I would like to change the default value in management studio for our guids to NEWSEQUENTIALID(). When I try and do this I get an error "error validating default value for column".
I just came across this one myself. I imagine that by now you already have a solution, but I'm posting for the benefit of the next person to come across it. You can safely ignore the error. When you get the error dialog, you choose "No". When you try and save the table, you'll get a pre-save validation warning (and you choose Yes to indicate you want to attempt to save). Or you can always use ALTER TABLE.