If the game crashes randomly, it's possible that you are either running out of memory, or are playing on one of unstable Intel processor chipsets.
In addition to the crash folder (from Documents/Paradox Interactive/Victoria 3/crashes) a DxDiag log file would help us verify if it's caused by these hardware issues.
You can get the log file by opening Windows Start Menu -> typing "dxdiag" -> opening the program -> clicking on "Save all information" -> upload the resulting txt file here (archive it first if the forum blocks you from uploading raw log file).