I used to have that happen to me. Landing sidways like that is one of the worst feelings, worsened by the fact that you know its going to slingshot hard to the other side after you land it (If you land it). It didn't matter what I did to the shock or how I how I hit the jump face - right side, left side, over the front of the bike or hanging off of the back, weighting the right peg or the left peg or even weight perfectly lined up, you name it and I tried it. It would normally occur on faster jumps where I was carrying alot of speed and it always drifted to the right. What cured it for me was ignoring the chain alignment marks on my swingarm. One day I just noticed my sprocket wear was really bad on the inside, but the marks showed that it was aligned. I decided to just align everything by eyeballing it and just trying it to see if it helped even out the sprocket wear...Well, it did, and as a side benefit it fly's as straight as an arrow now unless I really screw up on the jump face. I now use an alignment tool for total accuracy. Your shock could be off as sugested above but I would start resolving this by rechecking your alignment so that there is no doubt of alignment and then go on to the shock if your flight does'nt improve. Messing with the shock can get confusing and time consuming sometimes. Good luck, I know how you feel.