vdi verr_not_supported - Header corrupt

[mpack]

As far as I know damaged system files will be replaced with original ones (since Windows XP), so maybe I won't even notice if some files where damaged after the update.

Not quite. If a file is naively replaced with a different version then XP (and later) sees that and reverses the change. It prevents the bad habit some Win9x era programs had of replacing system DLLs with whatever (older!) versions they needed to run. However XP doesn't do a full byte for byte comparison on startup, that would take way too long, so corrupted files will not be detected... unless there's a manually started full system check which does it. E.g. there's a Windows tool called sfc, but I don't know in detail how it works.

In any case when you do a proper Windows update, both the system and backup copies of the DLL are updated... otherwise all updates would be reversed.

[roemer2201]

sfc runs through my system without any issues.

I just installed the new updates which arrived since I did it the last time, it looks like this also runs smoothly...

No risk, no fun. I'll increase the disksize by 20GB and then fill up this space with some files. Lets see what happens.

[mpack]

You should make a backup of course, before trying that. Hopefully you've learned that lesson now!

If the drive size is still maxed out then you might want to compact it at some point, using CloneVDI. If you keep the same filename and select "Keep UUID" then the compacted clone will be a one-for-one replacement. VBox has to be shut down at the time of course. That would be the most reliable way to compact a drive in future.