This error occurs when Cart32 attempts to read a file that either doesn’t exist, or has improper permissions on it. An overview of permissions to run cart32 can be found here.
If you have checked all the basic directory permissions then Cart32 might be trying to read or write to a file outside these directories. For example, Cart32 might be trying to read template files which have been moved; or Cart32 might be trying to write to an export file which it doesn’t have access to. The possibilities are very high for any of these. For this reason we recommend getting a program called Procmon (or on WS2003 and above, Process Explorer). These files are free to download and install. You simply run this tool on the server and tell it what to look for (in our case ACCESS DENIED) and where to look (in our case, everywhere which would be an asterisk).
When you try to access the page where you are getting the error again, Filemon (or Process Explorer) should light up with errors showing you what file was denied access to. Once you know the file/folder that is causing the problem, you simply add the proper permissions to it. The permissions should match the permissions you set on your cgi-bin folder for Cart32.