Whereas I get most of mine from over-running the end of malloc'ed arrays.
Sometimes the invalid placed data gets put in a harmless variable,
or the data itself is harmless in the wrong variables....
Othertimes WHAMMO!!! Instant week-long headache.

But I gotta agree with JCL, this particulat type of fault can be a bugger to track down.
But thats OK, as I find that I improve 'dirty' coding-technique areas as part
of the bug hunt process...