[Daynarr]

Well, I always play with 250 systems, use my mod for more types of standard systems, play mp3 music and have a load of other mods (including Mephisto's). Also I have 4 different installations; 2 for my mods in progress, 1 for playing and 1 original patched to 1.19 with no changes in it. I don't remember having ANY range check errors so far in any of those installations.
It is quite possible that you have something on your computers that causes this problems; hardware (graphic cards or sound cards with possibly old or bad drivers, defective components etc.) or software (some programs and anti-virus programs can cause problems). Check anti-virus first.

If you cant figure it out, send a mail to MM with your save games that contain that problem, describe that problem in details and don't forget to specify your computer configuration. It is most likely that you have something that I don't that causes you guys these problems.

As for strategic combat errors, I almost never use strategic combat so, most likely, that is why I don't get errors. However that one sounds like an big, ugly, slimy bug that just begs to be squished. You definitely have to send saved games with it to MM.