Ok, great. That info gives me some things to try out. Thanks for all the feedback. Barbara, when you change the mode are you doing that manually?

The database stays in full mode. The optimization job is out of the maintenance plan wizard so there's no extra configuration in it.  It's unknown how large the initial size of the log was, but...

More info, prior to this error I have:

"Cannot insert duplicate row key in object 'sysmergeschemachange' with unique index 'schemachangeversion'.

I can't find any duplicates (unless I'm looking in the wrong place),...

A little more info on this. I've confirmed it's hitting the last-created index on the table. Eg. id's indid in sysindexes =2. If I create an additional index on id,...

Thanks, I'll give it a shot.

Yes they are.