Juan, I've seen this quite a few times in a commercial VFP5.0 application named SBT (it's an accounting system). My solution was to upgrade to NT Workstation. Probably not the answer you're looking for, but you might want to surf around the web looking for keywords including SBT and 10H and I bet you'll find something. Kevin E. Stroud Hi My application (.EXE) is generating this error message: This program has performed an illegal operation and will be shut down. Details: MyApp caused an exception 10H in module vfp500.dll at 1006ba7e. It happens on my W95 client every time i close a preview window and select a different menu item. What's the problem? Thanks Juan Carlos