How to Move Servers and/or Change Directories
If you moved servers have you changed all paths to the new server paths in the admin options and permissions on the data and uploads directories are 777 permissions recursively?
Are file uploads on in PHP and safe mode Off?
If you have your image processor set to GD2 is GD2 in your PHPINFO?
Basically without knowing more info on how things are setup it is hard to say what your specific issue would be.
You can send an admin url to the contact us link for me to check your paths and settings etc