Changed value in Registry

Solution 1:

Process Monitor will let you track Registry activity in realtime.

Solution 2:

I use regshot (freeware) it allows to create snapshots before and after the change (for example an installation) Afterwards you can compare the snapshots and find all changes.

Solution 3:

Process Monitor also allows a myriad of filters to be set - so you could, for example, filter by process and only see the effects from the Symantec process you mentioned.

And if you're not sure which process to monitor, Process Explorer (another SysInternals tool) lets you drag a bullseye over an application to identify the process in the Process Explorer window.