This is the second time I encouter it: when I use the auto-replace feature strange things happen with the total active (and as result from that with the creedit limit). After a few months it restores just to normal values...
I don't know exactly how to reproduce, but I think replacing a line with other vehicles is sufficient
(http://nathansamson.be/simutrans-active.png)
(http://nathansamson.be/simutrans-credit-limit.png)
Nathan,
thank you very much for your report. After a lot of fiddling, I have eventually tracked this one down and fixed it. The fix will be in the next release. Thank you for the keen eyes!