The actions you suggested were tried numerous times. Using a registry keyword search for "SafeKey" and for "McAfee" will yield several items that can be deleted but each will regenerate upon restart. This was a new Dell PC package that included McAfee. McAfee was deleted but the error popup remains (possibly an attempt to offer an McAfee upgrade but the destination files have been deleted). As I chose not to use McAfee on this PC, all McAfee files and folders have been deleted. I appreciate your help.
Try removing all the Dell bloatware as they may have a key that pushes their deal with McAfee. Check your Control Panel > Programs and Features to make sure you don't have McAfee Security Scan Plus accidentally added the last time you updated Adobe products, also if you use WebAdvisor that will also occasionally remind about other products.
I had the same issue on a customers computer and I resolved the pop up message by renaming the ipuninstall.exe file to OLDipuninstall.exe in the C:\program files (x86)\common files\, Rebooted and the message "safekey could not write to your hard drive " did not pop up. not the best way but works and is stable.
Thanks for the info. Strange that this error still comes up considering that Safe Key has been EOL for almost 2 years now. We have this noted and will apply it in any future contacts we may get.