I will forward this thread to Beat.
Dont know if he can suggest code changes.
In other cases basically people ask their provider to move their account/site to a shared host that allows these functions.

rw1 wrote:

i asked my host to enable exec () and they replied:

"I am extremely sorry to say that exec() function is disabled on the shared server in which your account is hosted.

This is done in view of security on the shared server".

So can anything be done? Will this problem cause problems with the functionality of my site?

No worries to have.

This is happening in configuration screen only, and does not affect your site or CB functionality.

It is used to auto-detect which image libraries (used to build avatar thumbs) are presently installed on your hosting server, in order to propose them in the configuration. As ImageMagic and NetPBM are independant programs, CB tries to invoke it.

I'll see if there is a way to not display those warnings for 1.0 stable, but no promises.

Anyway, on a production server, you should disable warnings display (either do it in global configuration if hoster allows, or ask hoster).