here are some suggestions:
On the Client PC
1) Turn off UAC.
2) Turn off Simple File Sharing / File Sharing Wizard.
3) Turn off Windows Firewall.
- Steps 1 to 3 might be done using GPO
On the SEP Manager if you use the Client Deployment Wizard or the Push Deployment
4) Include the file SEPPrep.ini within the same location with the renamed SEPPrep.EXE and required install files (whether you use a single EXE package or a non-single package).
Hope those can help.