U have to delete them
ive had similar problems where a BSP once looked at crashes. only way to fix it is to remove it.
you may not need to remove all bsps, it may just be a single bsp, it may be all the bsps that are the same bsp, or it may be every bsp.
IF before crashin ur instrument panel becomes the same color as the ground color of the lvl, then this means that you simply have too many polys in the vision field and must remove some
If its the latter, what the hell are you doin puttin so many polys in one spot, thats definetly not gonna be playable even at half those polys if its just crashin, for example see Hons's lvl Spiders.