If you have UAC enabled you can start a program with administrator rights using "Run as administrator". But after disabling UAC this entry has no effect any more. As instance on my computer a have two user accounts. One for Internet and one for local usage. But some apps on my internet account need admin rights. This is an workaround for that problem using Sysinternals' psexec:
0) you need to have an (admin) account with a password set, it won't work without having set a password to that user, i call that user "Administrator" here
1) Download Sysinternals "PsTools" here: PsTools
(direct link: http://download.sysinternals.com/Files/PsTools.zip
2) Extract the zip file to "C:\Program files\PsTools"
3) Check wether "psexec.exe" is within "C:\Program files\PsTools"
4) Press Win+R and type "regedit"
5) navigate to "HKEY_LOCAL_MACHINE\SOFTWARE\Classes\exefile"
6) create a backup: right click the key "exefile" and "Export" it to any folder (remember that folder if my workaround doesn't work for you)
7) navigate to "HKEY_LOCAL_MACHINE\SOFTWARE\Classes\exefile\shell\runas\command"
8) change the value of the string "(Default)" to "C:\Program Files\PsTools\PsExec.exe" -i -d -u Administrator "%1""
9) delete the string "IsolatedCommand" (don't delete the value only)
10) you have finished
When using "Run as administrator" now a console will appear where you have to enter the password of Administrator.
Important note: While typing the password no letters or signs will be printed out at the console! Just type and press the enter key.
If you sometimes have problems with this solution you can backup the changed "exefile" key. So you can easily import the original or the modded backup.
@Admin: Please move this tutorial to the tutorials forum and delete this line