Error message while trying to start Point and set up SP6
Last week, I installed 7.4 SP6 and everything was working very well, but today, when anyone tries to start Point and set up SP6, he gets the similar error message:
"This installation package could not be opened. Contact the application vendor to verify that this is a valid Windows Installer package."
So, I've reverted everyone to SP5.
Also, I have done this with a cached set up, and without installing a cached, the same error message shows every time.
Even on a non-cached set up, the error message shows before it is downloaded.
Last week, the handful of devices that deployed SP6 is still working very well.
I need to solve it. What is the reason behind this?
Please help me.