Getting Warning message when opening Platform. Want to get rid of it.

I am new to this. I installed the Portable Apps Platform on my USB and installed about a dozen programs I use, also on the USB, from within the platform program by placing checks in the boxes. They seem to all have installed properly and open just fine.

But every time I open the Platform program by clicking on start.exe (I believe that is its name), I get a Warning message which says that my autorun file has been changed by possible malware, so I should run an AV program. I ran the Clam Av and other AV programs I have (Malwarebytes, etc.) and there are no infections.

I would like to get rid of the Warning message, which appears every time I open the Platform. Please tell me what I should do.

Thanks,
Menomena