you need to revise when the Get displays the error. This can happen when modify a object in Siebel Tools. If this problem occours in a local database, you can generate and extract a new database, if this problem occours in server database, you need see the logs (Siebel Tools logs) and solve this problem.
Can you do one thing compare the SIF files of the project Symbolic String from your local and the one on Server? You can do this by archiving the project Symbolic String on Server tools. Then take that sif file and compare it with the project Symbolic String available in your local. See what differences you have in your local. Make a note of that and then you can delete those objects which have difference. Once done first do a get of Project Symbolic String only. If its successful, then you may proceed with full get.