Trouble with FileVault

Hello,

i run Mavericks on my MP late 2011. After the repair of the graphics-card i decided turning on FileVault, because of my personal data. Everything worked fine: Encryption, restart of the Mac, login with password.

After my third login, after three restarts, my password is not accepted. Fortunately i owned the recovery key, which i entered successfully. But after the fourth restart, the recovery key was not accepted anymore. Fortunately there was an another account, where the recovery key could be entered successfully.

Now i have FileVault switched off.

Does anyone have similar experience?

With best regards

Achim