Plugins will not let me change settings and will not auto install

I cannot install plugins automatically, I get stuck at the downloading page.

Once I install plugins manually using Filezilla I attempt to change the settings e.g. “Fast Secure Contact Forms” and the screen stays blank with Fast Secure Contact Form Options at the top and white space below.

Why are my plugins not downloading, and why when they are downloaded and activated do they not work.

All help is much appreciated.