Many Params-Validate versions before 1.20 have a bug in the XS code that could cause the corruption described. (Versions before 0.50 did not have an XS implementation and so would not suffer from this problem.)

If you are using an older version, you can check if you are suffering from this bug by persuading your program to use the pure perl implementation. (Read the source of Params/Validate.pm on your system to find out how to do this.) If the problem goes away under the pure perl implementation, then you probably are suffering from the bug in the XS implementation.

The bug was addressed in versions 1.20 and 1.23.

1.23    2016-03-26
 
- Fixed some Perl stack corruption bugs. Based on a proposed PR from Tony Cook
  plus some additional changes. GH #8.
 
- Fixed tests with Carp 1.01 (shipped with Perl 5.8.3). Patch by Andreas
  Koenig. RT #113318.

1.20    2015-06-28
 
- Fixed a bug with stack handling in the XS code. If a callback sub caused
  Perl to reallocate the stack this could trigger weird errors of the form
  "Bizarre copy of ARRAY" from Perl itself. Fixed by Noel Maddy. GH #5.

See also https://rt.cpan.org/Public/Bug/Display.html?id=86811