I was able to get igo to stop having out of memory issues on my D90, here is what I did...
I turned off the 3D map veiw and put.it to 2D, I turned off all those extra tjings that show up on the.map- gas stations, air ports, poi, ect... It seems there was just to much stuff trying to load. My suggestion to anyone having this out of memory issue is to turn ALL the extra stuff off, see if it works without freezing. If it does, start turning back on only the things you really want... Hope this helps!