What does “ShellExecuteEx failed; code 18” mean (on vista)

Question

A buddy of mine has been getting this error mesage when trying to run uninstall programs andor new program apps, windows just shows "ShellExecuteEx failed; code 18" and refuses to run the program.

Answer 1

This Microsoft article explains the system call he tries to make.

A little googling the error codes suggests that 18 means SE_ERR_ACCESSDENIED (In the list the previous one is 11 and the next is 27)

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