Popped in to say it might be your DVD Drive. I've had an issue where my DVD drive wouldn't read my Arma 2 disc, then tried it another on computer and it worked. I replaced the drive shortly afterwards.
Even though, your drive can read your UBM disc, it probably hates the SH4 disc for whatever reason. I'd say if you have another DVD drive laying around somewhere, it wouldn't hurt to use that instead.
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