hard drive might be going bad. could be a low voltage issue too, I've seen that on the "newer" Atari/Midway games with hard drives.
I know you can't magically pull a Blitz/Showtime hard drive out of your you-know-what, but if you got a meter handy I'd check the +5 voltage first, I think what you're looking for is about 5.10V with Vegas boardsets... maybe someone else with more experience with these will chime in.
if that number's too low, it'll affect your hard drive if it's not getting enough juice, I'm going to assume your hard drive is plugged into the port on the game board and not the power supply.
otherwise, your hard drive might just be bad too, if it does it in the same spot every time, that is. rom check is kind of pointless on these, run the hard drive check instead, if you get a lot of errors, that'll explain some things.
user ToplessZ sold compact flash kits for these, but last I heard from him he was going into the air force academy or something and wasn't going to be making/selling the kits for a few months, though I saw him post some other items for sale recently, maybe send him a message. make note of which version your roms are, I think it displays it on power up, cause the hard drive revision has to match or else it won't work.