I think I may have found out why Valkyrie Profile crashes and WWE doesn't start on 2.71 SE-A.
Since in SE-A, the PSP launches up 1.50 first, then that in turn starts 2.71. Well, Dark_Alex put some of the 2.71 files in flash0:/kn, instead of flash0:/kd, because thats where 1.50 resides. I think that since some games need the updates .prx's, when they go to the kd folder, they get incompatible 1.50 .prx's.
I think something will have to be added in SE-A so that it redirects flash0:/kd to flash0:/kn for UMD games. I hope Dark_Alex fixes this on SE-B (or whatever its called).