I would say you should disable the startup entry for fences on one of the accounts.
1. Logon to the account, hold windows key +R
2. Type msconfig , hit enter
3. go to startup, find fences and uncheck it.
4. Then reboot and it will be disabled. (I'm not 100% sure it will be disabled on both accounts or just one.) It may depend on who is administrator.
---Another option that may be a possibility-----go to your start menu and go to all programs, then find the folder "startup." If fences is in this folder, simply remove it.
I hope that I was somewhat helpful.... I don't know a whole lot about how to use multiple accounts.