Hi Eric,
Interesting thing I would like to tell you is that this server is started on daily basis. Then what could be the problem.
But as you are saying I would do the following thing. Please make me correct if I am wrong:
1. I would remove the UDF.
2. Again I would add the UDF using code. (No client system will be on during this process)
3. Again I would try and save the value in that field.
Regards