TeaTimer, which is a tool use by Spybot that monitors the any attempts to change the Windows registry. This is to prevent malwares from installing itself behind your back.
Windows registry is a database use by Windows Operating System.
Usually, no program are suppose to change the registry except when you install a new software or hardware.
The reason why Spybot monitor registry changes is because many spyware and trojan modify the registry to run the spyware & trojan automatically when Windows/internet explorer start up.
If you detect some programs are trying to change the registry but you are not installing new software or hardware. It means that a spyware or trojan is trying to infect your system. You should deny changes so that the spyware or trojan cannot run automatically when you start your windows.
You can turn it off by aenable the advance mode and go to Tools -> Resident -> untick Tea Timer.
I like spybot because I found that it is a better strategy than other anti-malwares. Instead of trying to keep the virus/trojan/spyware/adware signatures up-to-date ( impossible task because new one keep appearing ) Spybot try to stop UNKNOWN malwares from infecting your system by using teatimer to deny unauthorise changes to registry.