Everything that uses Windows Installer installs in silent mode

As the title says, for the last 2 days, everything I've tried to install so far (mostly different games), has installed in silent mode.
At first I thought that their respective setups didn't work, since there weren't any windows popping up, but after checking Task Manager and noticing that they were using CPU resources, I went to the default install directories and saw that every single time I've tried to install something and thought it didn't work, it in fact did, just in silent mode.
Now all of these installers have only one thing in common AFAIK, and that's Windows Installer.
Is there perhaps a setting for WI to enable silent installs by default, and if there is, how do I turn it off?

P.S.
If I posted this in an incorrect section, please move it to an appropriate one.

Yes, all those installations work perfectly normal on other PCs, and worked fine on mine in the past.
I don't use System restore due to some bad expeiences I had with it years ago.

Update:
It is possible that it's InstallShield that's causing these problems.