thing is for me and i have this firmware i dont have crashes in other games at all not even lag, however my situation is a bit odd as after all the crashing started with skyrim i had a break and was just flicking through my XMB when the playstation crashed and because of skyrims crashing and corrupting save files i instantly panicked and thought skyrims crashes may have corrupted an OS file within the PS3s system files, so i restored my ps3 back to factory settings after backing it all up (took 12 hours in total) since then skyrim is the only game to crash the rest work fine
the only exception iv had is hunted crashed twice yesterday (i only got it yesterday so was brand new to me) but after realizing it was bethesda game, did a bit of searching on the forums to find this game had reported crashes in the areas it crashed for me so have chalked that up to its a bethesda game they crash....so i dunno but for me i dont think its 4.00 firmware as all my other games work fine and dandy with the firmware....
as a reply to the post above me yes it helped me loads did reformatting as the crashing stopped for a little while but then slowly came back but this time its only on skyrim and the beginning of hunted nothing else on the ps3 thats why i think skyrim may have [censored] with a OS file when it crashes while accessing the HDD
I have now put skyrim away untill its fixed for fear of any more potential software damage