PHP Error message when resizing/uploading images

[Nashboy]

I have recently began using the Kubrick theme. I amended several config settings to get the coppermine pages display to my satisfaction. Unhelpfully, I didn't make an exact note of what changes I made.

I normally upload pictures at 1024 x 768 resolution and these display and upload fine . When I upload smaller sized jpegs or try to resize them I get the following (or similar) PHP message:

Warning: imagecreatetruecolor(): Invalid image dimensions in *my.website.com*/coppermine/include/picmgmt.inc.php on line 216

Furthermore previously uploaded thumbnail and original size pictures display ok but intermediate pictures don't display at all.

Please note again this problem only applies to non standard (i.e. not 1024 x 768) sized pictures.

Thanks a lot