is there any solution to the locked sfi.dat problem?

There are a few posts about that issue, but it looks like there is still no way to fix this by changing some settings. Using the install CD is not an option, if you want to use other tools.

So, can sfi.dat be unlocked somehow? The AV is turned OFF here.

What version of CIS are you using? Where is it intruding? With System Restore?

It´s 4.1.150349.920, & yes, it ist preventing the system restore function from working.