I have reinstalled my laptop with a different Linux-distribution.
This screenshot shows my new install (top) and my old install (bottom):
I am using the same wallet.dat, and I copied it back to the old install to create a screenshot of the old situation. Everything used to be fine, but in the new version it keeps showing 594.46684 mBTC as Pending. I know it's not send by real transactions, no money is coming in. Nothing changed in the Transactions-tab.
I have had 2 "weird" transactions in the past: the first said it's a double spend, the second I actually did a double spend to fix a zero fee transaction that was stuck for 2 weeks. But the total amount of this was much less than what's Pending now.
Anybody knows what is going on here? It makes my Bitcoin Core looks messy, and it makes it seem I have more mBTC than I really have.