Desktop plugin won't install

Desktop plugin won't install

I've used the Zoho Assist desktop plugin for a long time but uninstalled it recently after a problem. I've downloaded it again and tried to install it. But I keep getting the error message "The feature you are trying to use is on a network resource that is unavailable. Click OK to try again or enter an alternate path to a folder containing the installation package 'ZohoAssist.msi' in the box below." The path displayed in the Use Source box is the location that contains the ZohoAssist.msi file.

If I click OK, I get a new error "The file 'C:\Users\Steve\Downloads\ZohoAssist.msi' is not a valid installation package for the product ZohoMeeting. Try to find the installation package 'ZohoAssist.msi' in a folder from which you can install ZohoMeeting."

If I click Cancel instead of OK, I get the message "The older version of ZohoAssist cannot be removed. Contact your technical support group."

This is a stand-alone Windows 7 PC. The MSI is in my local downloads folder.