When starting ArcMap, a Windows installer dialog box appears and attempts to install ArcGIS Desktop.
Some anti-virus programs, such as Trend Micro Office Scan, erroneously delete the file regobj.dll from the <system drive>:\windows\system32 or \winnt\system32 directory. This triggers the self-repairing feature of the ArcGIS installation to replace this file.
Note: This file is NOT a virus; it is a required file which allows developers to access the registry from an ActiveX control.
Do not let the anti-virus software delete this file; follow the steps below to prevent deletion.
Note: If the problem persists after excluding and replacing the file, Trend Micro's Damage Cleanup Services may need to be updated. This is a known issue with the Trend Micro Office Scan product. Please contact Trend Micro for the update.