My colleague got the error 1001 when trying to install VC 5.6.0 client on her new laptop (Win XP Pro).
Deinstallation doesn't work (following:
1. Make sure that the VisualCronService.exe is not running. You can stop the service in Control Panel->Administrive tools->Services
2. download installutil.exe to your VisualCron folder (%program files%/VisualCron) from here
http://neteject.com/installutil.exe 3. Download and install the Microsoft cleanup utility from here:
http://neteject.com/down.../VisualCron/msicuu2.exe 4. open a command prompt. Go to the VisualCron folder
5. write: installutil.exe /u VisualCronService.exe
6. Start Windows Install Cleanup from the start menu. Select the VisualCron installation and click on the Remove button.
7. You can now choose to install again or completely remove the VisualCron folder
After Step 5 the error message comes again.