A colleague of mine has recently discovered an unfortunate fact SPLAT R75.40 has no support for 4400 appliance.
Everything works fine with R75.30, but after upgrading to R75.40 appliance status in SPLAT WebUI shows error code = INITIALIZE_CP_SENSORS_FAILED message. There is a SecureKnowledge case SK79800 mentioning incorrect drivel load. Unfortunately specific drivers are missing for 4400 appliance.
After numerous hours spent in resolution and a support call, the issue is still there. In fact, Check Point has confirmed that R75.40 SPLAT does not work properly on 4400.
One can use either GAIA R75.40 flavor or upgrade to R75.45. The last option obviously requires Management side upgrade as well.