This is a tough one. I first deleted my P-61 entry in the air.ini I made 2 days ago, that does without all the japanese and most of the soviet planes and all 7 worked without any fault. Again and again, no crash. But then I tried it on my full europe air.ini, minus the P-61, and it crashed again as usual. I then deleted all the extra russian planes I added myself, and the crashes continued as before. I finally deleted ALL yaks, remained with only 2 Ba.65 versions (K.74 monoposto and arconel if that matters) again crashes...Now please, but PLEASE I don't want to hear that I may reached the ultra-cursed java memory limit because I don't know how I can run all these Yaks like the (early style canopy) Yak-1PF and the Yak-9DD etc. with any problems and Ba.65 crashes.
And my experience says at the end that what is "4.09 only" and what is not, is very relative. I can run Yak-9DDs, P-39N field mods, Hurricane "sunsguns", Fw 190A-8/9 1.65 atm, Avia 534 series III etc. without any fault, if that says something to you...
An idea is that dreamk works with a SAS modactivator and the plane somehow conflicts with something that exists only in UP3.0 and/or DBW 1.6.