I have two RZR 2007. On Both units the front 4x4 started going out intermitinly then went out completely after only 120 miles. The dealer said he fixed the first one under warrenty and it went out again after five miles the other one is still at the dealer to be fixed.. Anyone else had this problem. I run these in sand only other than the 1/4 mile trip from the staging area to the dunes. I had the 4x4 button on all the time. any help woud be great.