Some of the mods use preloading of assets in a non strategic way.

This applies for example to Rainbow Six soundmod steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=32931316

In the mod's XML configuration files, find and replace preload="true" to preload="false", now I'm not an author of any workshop items for this game in question, so i don't know which of these should actually be preloaded.
This can be done quite quickly with Sublime Text 2 or Notepad++ ( Free )

I've changed all to non-preloaded in Rainbow Six soundmod and it works flawlessly.

Bottomline is that something has changed in the game's asset loader and the game crashes after trying to pre-load too many assets.

~~Toodles