Why is my Action Center tray icon missing?

Your Regedit suggestion worked, only I didn't have to restart.  The effect was immediate.  Thanks, dude! :)

I have a solution for you all ,i think especially for GTA_doum ,look here post #8 http://www.sevenforums.com/tutorials/19085-system-icons-enable-disable.html

try "gpupdate /force"  (without " ) this command in the cmd/dos (with admin rights) worked to me. it resolves everything.

you can also do this workaround http://smartnetadmin.blogspot.it/2011/11/action-center-settings-are-greyed-out.html ,good luck , i had the virus too, i had removed it from windows 7.

It seems that after I set it to disabled the second time, restart, and wait for several minutes (after the other three has appeared), it comes back.

I got Windows 8 Pro (with Media center), same problem. I have the dll file. I tried registry and no luck. I tried gpedit, and after I disabled the Remove the Action Center icon policy, my icon comes back. After I set it back to Not configured and kill explorer and restart explorer, my icon is gone again, and the Action Center item is grayed out. Hope that information helps. I'll try to run a process monitor and see what happens with gpedit.

EDIT: after I set the policy to disabled and back to not configured, my icon is gone; but then after I set it to disabled, my icon is NOT back this time... so I don't think process monitor can help me this time.

InfoTip                          REG_EXPAND_SZ         @%SystemRoot%\System32 \ActionCnterCPL.dll,-2

Localised String           REG_EXPAND_SZ         @%SystemRoot%\System32 \ActionCnterCPL.dll,-1

There shouldn't actually be spaces in those paths, should there be?