It seems that it’s fixed, I did what you said WFBrian and upped the memory_limit value in the php.ini within XAMPP since we have 1GB of RAM. However I did not get any memory_exeeded message in the logs. I also added our external ip adress to the whitelist. Now if I run a scan, I don’t get locked out.
It’s a really weird issue though, why would I get locked out in the first place? The only thing I do is a scan, plus I run it locally and the software clearly states that it automatically whitelists private ip addresses like 192.168.x.x.
I noticed that after some time, the local site is reachable again after a scan.