Does the error happen when you try to synch, or does Access crash as
soon as you attempt to open the database?

The replica is probably corrupted and needs to be repaired. If you
can open it but not synch, then you should make a copy of it and
then try to compact and repair the original.

You should also try creating a new replica from it in code, since
the problem that causes Access to crash may be one that does not
actually involve Jet.

You could also try synching with the problem replica from another
replica, for the same reason.

If the replica won't open in Access and all efforts to communicate
with it without having it open also fail, then you probably need to
have the MDB file repaired by someone like Peter Miller
(http://pksolutions.com). The replica might lose replicability in
the process of recovery, but at least you'd be able to get the data
out of it.

Otherwise, you should look through the information in Tony Toews's
corruption page:

 http://www.granite.ab.ca/access/corruptmdbs.htm

None of that specifically applies to replication, but when a
replicated MDB is corrupt, the advice there still applies. I've
found, however, that even the slightest corruption in a replica
usually leads to the loss of replicability, even when 100% of the
data is recoverable. That means manually recovering the data out of
the repaired MDB and applying it to a live replica. It's a lot of
work, but better than entirely losing the data.