The problem wasn't that explosions were occurring at all, the problem was that they wouldn't STOP occurring, lol. Multiple explosions every second, non-stop, only pausing when they lagged the hell out of the game ticks, until the game crashes. I fixed it by changing the world gen to Biomes o' Plenty instead of Default, whereupon I got one or two explosions after loading into a brand new world, and then blessed silence and ability to play. FPS and tick lag problems have been few and far between since. I'll have to try the new patch with Default terrain set and see if it works better.Glenns gasses are exploding somewhere underground.......
Main menus background is done by a mod. Dunno which one.
Thanks for saying about the menu background, it was driving me nuts thinking there was some kind of weird texture problem.