:(Hi there-my registration ran out with avast last night so I had to get a new licence key, which I duly did, and typed this number in. The key was successful but I seem to have lost the grey resident protection icons in my task bar! How can I get them back please?
Welcome to the forums, bridget. 
If you are using XP for your OS, try using the repair function under Add/remove programs. You must be online to do this.
Repair is unlikely to work in getting the icons back, I can’t recall it working in the past.
avast! icon missing - As a temporary measure you can create a desktop shortcut for this file C:\Program Files\Alwil Software\Avast4\ashDisp.exe (the avast icon and interface to the providers). Right click on the file and select Send To, Desktop (create shortcut).
What other security based software do you have that might block new startup entries, e.g. Spybot S&D (TeaTimer), AdAware (AdWatch), SpySweeper, Spyware Doctor (StartUpGuard), PrevX, WinPatrol, ProcessGuard, etc. ?
Check the option in the Appearance tab of Program Settings. Or Make a link to ashdisp.exe in your startup folder.
Or Add the path to ashDisp.exe into a value named avast! in the Windows Registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run (see c:\avaststartup.reg if help needed)