OK all I've tried a lot of suggestions on this problem and can't get it. I have a 2k8 server that was backing up to this (it's a developer box not really a server) 20 days ago and randomly stopped. Reinstalling the software results in after the password box. Install and reinstall works on other machines.
operation cannot be completed at this time
I have removed av, turned off firewall, put administrators and everyone on the rsa folder, I have made sure I have makecert.exe on the pc, I have updated (doing more as I type this) I have created new users.
And still I get nowhere. The laptop is 2k8 64 bit and does host virtual machines if that makes any difference.