Removing software

Download and install RevoUninstaller (http://www.revouninstaller.com/start_freeware_download.html)and do the advanced uninstall.  This will use the problem programs built-in uninstaller and if that fail or leaves stuff behind, it removes registry entries and files related to that program in one easy to use wizard....

I downloaded the Free Trial version and ran the Uninstall and didn't succeed. The funny thing is that when I want to install a new software , I get the exact same error message

Are you running an AirCard, or some kind of 3G wireless?
You may need to update or repair the MS Installer.

http://sierrawireless.custhelp.com/app/answers/detail/a_id/33/~/why-do-i-receive-error-1720,-1721,-1722-or-kill_watcher.exe-script-error-

I've done the Regsvr32 wintrust.dll and I've also updated the installer as recommneded . Still having the ame problem.

Yes I'm trying in install a Sierra Aircard AC310U 3G Wireless

hmmmm... in Control Panel > Admin Tools > Services, is Wireless Config running?

look if this helps :  http://answers.microsoft.com/en-us/windows/forum/windows_vista-windows_programs/error-1720-there-is-a-problem-with-this-windows/0b965fe8-2d16-498c-bb88-395911e13146

Tried all of these and still the same problem.

Worked fine

tx for feedback