Thanks redseujac!
Following your lead, I found some other small bits on the Web that confirm your findings. For example:
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(1)
{5E6AB780-7743-11CF-A12B-00AA004AE837} is for Microsoft's Internet toolbar and {75048700-EF1F-11D0-9888-006097DEACF9} is for Active Desktop.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(2)
"NoEncrypt"=dword
"NoLog"=dword
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(3)
User Key:
System Key:
Value Name: NoInstrumentation
Data Type: REG_DWORD (DWORD Value)
Value Data: (1 = enable restriction)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(1) Information only.
(2) Tested these. NoEncrypt does the logging in plain text instead of the simple rot13 encryption. NoLog turns off logging after a reboot.
(3) Apparently turns off userassist altogether -- did not test this.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I did some additional tests:
1. Deleted the entire key: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\UserAssist then rebooted.
2. The key reappears with no Count entries, but starts logging new activity.
3. If you used Nolog, Count has one entry (UEME_CTLSESSION, not encrypted), but nothing else is logged.
4. You lose the start menu list of frequent programs, as redseujac found. Since I sort of like that list, I probably won't use NoLog. :)
Why is windows doing all that logging? In my opinion, it was originally a tool for debugging and collection of data for frequency analysis by developers. Since it worked so well, they just adapted it to provide the "start menu list of frequent programs" feature. I may leave it with NoLog for a time to see if there is a noticeable performance difference. I doubt there will be anything noticeable.
Edit: At least one forum member has found an application (Microsoft AutoRoute) that apparently actually uses the UserAssist entries.