How can I get Unity to work on win7?

Hello,
I have a dell vostro 3550 with intel i5 2,3Ghz, 8 GB Ram and win7 pro 64 Bit.
I tried to install unity 5.4.2f2 (64-bit) as well as the 32-bit version.
Everytime I start the program it freezes after 2-3 clicks. When I minimize and maximize the window the view updates and I can see my last actions. Obviously I cant work like this.
I have already tried to set the performance settings on the Catalyst Control Center from high performance to energy saving like @darkshines said. It doesn’t work.

I have also tried to deactivate DEP in the system settings. It is still not working.
Has anybody a solution to this?

Thank you!

Try installing the latest .NET Framework linked and start unity after its installed
https://www.microsoft.com/en-us/download/details.aspx?id=30653 tell me if this worked.

May not be the source of the problem for you; but I had this problem as well at first. The issue came from my GPU having issues rendering Unity after a few updates. I figured this out when I replaced my GPU.

You should try 32 bit unity version