How I can I see the causes of why the game crashes?

stdout.txt and stderr.txt should help.
There is also the log of the last game (.stratagus-2.2/wc2/logs/log_of_stratagus_0.log) (you can replay it).

And in debug mode, you can attach a debbuger.

where are those files?, i mean "stdout.txt" and "stderr.txt". I thought they were removed

Yes, these files was removed. Instead output to files, Stratagus write stdout/stderr output to windows cmd console (like on unix). You need run stratagus from cmd.exe to see output.

I was playing through the game today and it crashed. then I ran it from cmd.exe in debug mode and when it crashed again, it said the following

Assertion failed at src/action/action_resource.cpp 452: next == source

That's it. it also mentioned above this that the ai just stands around confused when the resource is no longer available...any ideas? should the == be changed to a single = sign?

Assertion explain that we expected variable next == source (equality)
single = is for affectation, So the bug is not in Assert.
It seems to happen when resource (mine) become empty and is destroyed.
I will try to reproduce it this week-end.