Just to affirm Tomas's point, the Debug version initializes most variables
to zero. The Release version will not initialize anything 'naturally'
(meaning without you writing code to do so), and hence many of the variable
are often given a 'random' value upon loading ('random' in that they keep
the contents of the memory addresses they happen to get assigned to).

Thus, your new errors are likely the result of some variable that works fine
if initialized to zero, but don't work if not initialized to zero (or not in
some range, non-negative, etc.). Since an application doesn't always get
loaded at the same place and memory, and because even the same place in
memory can have different values depending on when you load your program
(that's why it's RAM not ROM...hehe), you can get random bugs and un-stable
executions of the Release version (i.e., it might do different things on
different runs depending on the 'random' nature of your variables) even if
it is totally stable in Debug mode.

Hope that helps!!!  : )