500 errors & problems with image upload after switching hosts

Hi ,

Please I need someone figuring out what could be causing this.

I switched my wordpress blogs from one host to another one .

They did the move for me with a full back up of my blog sites I had created in Cpanel.
(new host has cPanel as well )

Now I have problems ,when posting, or previewing post and uploading images.

F.e. I will make a new post or update a post and when I click on
preview or publish it will go to the 500 internal errror page .

When I upload images (I even retried the one I had previously uploaded without problems) I get these error messages :

Internet Explorer : HTTP error

and

Google Chrome : No data received
Unable to load the webpage because the server sent no data.

Reload this web page later.
Error 324 (net::ERR_EMPTY_RESPONSE): The server closed the connection without sending any data.

The image upload is now really disrupted .

While the post problems happen intermittenly.
It works about 70-80 % with error messages coming for the rest of it.

Is something installed incorrectly ?
I disabled quick cache,which is the only new plugin I have installed since the move,but that does not seem to make a difference.

Any ideas,please ?

Thanks