Bicycle Tutor

I have recently purchased new ISIS bottom bracket and crank arms. They came together, so they are fully compatible.
After installing, i have noticed that right crank arm is not spinning straight, so when i put chain on, chain is going left-right, and at this moment is not rubbing the front derailleur, but i am afraid that after few months of riding it will, if i don't find a solution now.
Bottom bracket is installed good.
What to do, is there some way to avoid that when mounting crank arm which i don't know?
Thanks!

Hmmm, it definitely sounds like your crank arm is not mounting evenly on your bottom bracket spindle. Take it off and take a close look at the crank and spindle to make sure all of the spines match up and there's no wear. If everything looks good, re-install the crank arm (it might have just installed funny the first time). If that fails I would take it to a good bike shop for a closer look from a trained eye.

It could also be that the crank/spindle are fine, but your chainrings are bent. Is the unevenesss the same on all the front chainrings? If not, it may be one is bent. In which case, you may be able to straighten it.

yes, came on my mind too....Smaller chainring (it is compact 34/50) is also not spinning straight. Sure, because his diameter he is going less to side.
I must add that crankset wasnt cheap at all.
I guess i will have to visit shop where i bought it...So far, it is mystery to me.