Hello, I've made a little program in visual basic which automatically copies patched files of solidworks 2010 to the right directory. When I copy the files I use: "my.computer.filesystem.renamefile" to rename the .dll to .dll.bak "my.computer.filesystem.copyfile" to copy the patched .dll "systel.io.file.create" to create an empty file whit no extension, this is to tell the program that the patch is already installed and so the uninstaller know's the .dll.bak file really exists. For uninstalling I use: "my.computer.filesystem.deletefile" to delete the .dll "my.computer.filesystem.renamefile" to reneme the .dll.bak to .dll The problem is that when it's removing the .dll a just in time debugger window pop's up which says the acces to the dll is denied. However, I am able to remove the .dll.bak propperly whit the same command. Renaming the .dll to .dll.del, then rename the .dll.bak to .dll and then removing the .dll.del also gives an error. Does anyone know how this comes? It happens with windows 7 and xp and I always run it as admin.