@ThereseLogeais - OpLocks means the 2nd user/workstation caches the same data file that is being shared over a UNC or mapped drive (which means this is not really an issue with mas 200). So let's say 3 users use S/O Entry all day. If we disable OpLocks, the 2nd and 3rd user run slower in S/O Entry. In the past the slow-down wasn't too noticeable but since Vista and Win 7, because it uses a different version of OpLocks it can be more noticeable.
@NancyHanson - you should get the same benefits of OpLock disabling by only making the server-side registry change and rebooting the server again. IOW, revert the workstation settings back to default. This way it won't be as slow as both sides having it disabled.
Having said all that, I'm not sure this is the cause of this issue. Go with Debbie's idea first as that's easier than anything else and would be an awesome solution. If it doesn't work, then setting the MAS 90 shortcuts on Win 7 PCs to run in XP SP3 compatibility mode is a good troubleshooting measure. This can be turned off once things calm down.
Usually license loss occurs when:
1) A MAS task isn't shutdown properly such as VI import that auto-runs, finishes and it appears to have completed but errored out before proper completion (like when chaining between 2 jobs and 2nd job starts before 1st completes).
2) The client connection is shut-down
Do they leave their PCs idle for long periods of time (such as all night long). There are some server settings related to how long it should wait before terminating a client connection (meaning you don't want a MAS task open when this happens).