Update needed everytime i restart my Mac Book Pro
After upgrading to Yosemite, everytime i restart my mac, a gray screen appers with an unknown user and the message "update needed'. It will ask me to introduce my password to proceed.
Then it will take several minute to login
Model Name:MacBook Pro
Model Identifier:MacBookPro9,1
Processor Name:Intel Core i7
Processor Speed:2.6 GHz
Number of Processors:1
Total Number of Cores:4
L2 Cache (per Core):256 KB
L3 Cache:6 MB
Memory:16 GB
Boot ROM Version:MBP91.00D3.B08
SMC Version (system):2.1f175
MacBook Pro, OS X Yosemite (10.10)