A word of warning for those that flash custom ROMs often on their Android smartphones and use Titanium Backup to backup and restore app & system data after a clean data wipe: only restore applications and application data, DO NOT RESTORE SYSTEM DATA. If you restore system data (even when flashing to new minor ROM updates) via Titanium Backup, there is a high possibility that you may encounter the “grey signal indicator bug“, which indicates that your phone cannot sync properly to Google’s services.
I recently had this issue when I did a data wipe on my Galaxy Nexus and flashed to AOKP’s newest JB-MR1 Build 5 ROM. At the time, I thought that it was a bug with JB-MR1 Build 5, but I found out that it occurred because I had inadvertently restored system data while restoring my applications, data, and system settings via Titanium Backup. I have tried re-flashing the ROM and GAPPS, but this had no effect. Apparently, the only real fix for this issue at this time is to do a data wipe and make sure you do not restore system data when using Titanium Backup.