Hmm, I suspect it's to do with the mod relying on DLC's you don't have (Forbidden Worlds and/or Stellar Phenomena), though I don't know much about Infinite Space specifically. What DLC's did you buy during the Steam sale (if any)?
DLCs should not make a difference with mod compatibility. However, not all mods enable the DLC features. Since infinite space is itself a planet mod, it may simple use its planets instead of the planets from forbidden worlds, thus there is no reason to have the colonization techs the Forbidden World DLC adds. So are those the only techs missing, and have you actually seen a planet you could not colonize because you need one of those techs?
As for the crash, a good general thing to try for any mod is to lower your texture quality settings (ship/structure/planet detail), mods make it easier for Sins to hit the 2GB RAM limit and lowering this setting lowers the RAM usage.
