Not a problem with antivirus or other programs interfering as far as I can tell. I have 37 other trainers on my computer that all work fine without a problem, Metro 2033 Trainer Patch 2 V2 however gives the following message every time it starts.
(I've changed location, privileges, compatibility, firewall settings, AV settings, re-downloaded, and everything else I could think of.)
"This trainer has failed an authenticity check and is no longer authorized for use. Please visit CHEATHAPPENS.com to download a legitimate copy of this file."