ntuserdatlog changes every few seconds

Is it usual that ntuserdat.log changes with every few seconds?
Look at this:

http://i2.tinypic.com/sno5k0.png

What can be the reason for this?

 

looks like strange activities

 

Yes, it's perfectly normal - ntuser.dat contains the user part of the Windows Registry which is constantly updated by Windows itself with the log file just containing the most recent changes.

 

Oh good to know, thanks for this info!

It looked scary.

 

Recently I've noticed that the ntuserdat.log of the administrator account on my pc keeps on changing. Last night it happened again/

I work on my own account and generally I leave my pc on running, locking my pc whenever I'm not on.

Anybody here any ideas on what might have caused it?

 

Most likely you have an application running as Administrator in the background (Windows services have such permissions by default). If you want to find the exact cause, you will need to use a registry monitor/firewall like RegDefend to identify the application and registry key involved.