PowerStore 4.01 problems

Hi
I have installed PS4 onto a site for a client and have the following problems. (I have submitted a support ticket but have had no response # 124531.)
Problems:
1. Will not save a design - whenever I try to save any design change it give a 500 internal server error as per:
"Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, (email address removed) and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request."

2. If I have my permissions changed to 777, I cannot access any part of the site, error as above but with all pages.

3. When I add a product and then add an optional size eg. a jar of product 14oz and 22oz, the main image appears for the first option (14oz) but no image with 22oz option.

I have uploaded the "fix" file as per Jason Byrnes post here showthread.php?t=19233

Any help or explanation would be greatly appreciated.
cheers
scott