This is a generic internal error message is generated if QuarkXPress runs out of memory while trying to allocate the memory needed for a string.
As these string are usually very short (a file name, a color name, ...), this internal error is most likely due to an overly aggressive anti-virus, or to Windows being almost out-of-resources. You should try to re-boot your computer. Also make sure that you are using the latest version of Q++Studio and the minimum recommended build of QuarkXPress, as this error could come from a bug which has since been fixed.
If the problem remains, please send the script to technical support.