Anyway, for those still interested in this, took the X to the service center and was told that the hubs might be the problem. First they wanted me to pay since it was out of warranty. I pulled out the warranty manual and said that 4wd was part of the powertrain which carries a 5 yr warranty. The manager agreed and after waiting a week for parts, the hubs came and was installed. Took the X for a spin around the dealer and still the same problem. The foreman comes out, test drives and after an hour on the lift, it's fixed. Stated something about the transfer case needing a slight ajustment.

Now one mechanic told me that in order to engage the 4wd, the X has to be in neutral. The other mechanic said it can be placed in park and then shifted to 4wd. Who is right?