Vista - random de-sync of library from another user

I am using Foldershare on two separate computers with two separate accounts.

For some strange reason, the 2nd computer would randomly become de-sync from
the folder about every 2 weeks. This would cause the files not to sync and
gives the error on the Foldershare site of "This member has no computers
synchronizing with this library." So I then have to select to sync up the
computer to that folder again.

The computers are in two difference locations and the option of
consolidating into one account is not needed at this time due to the fact
that its two different users.

Is there something specifically that would cause this to happen?

please help!