I have another problem with my Lexmark X85 - it has started feeding the page out part way through, portrait or landscape. I've tried all the obvious things- re-booting, re-connecting the usb etc. but no joy.
You can alter the paper size when you click PRINT in any Office/WP program but have you checked the paper size by going to Start/ Settings/ Printers, double click on the printer being used, Printer tab/ Properties/ Printer Settings? The above is for Win 98SE but should point you in the right direction. Just a thought!
Your thoughts made me double check (again) and I noticed that the spool settings were RAW and I remembered from somewhere that Lexmark prefer PMJOURNAL and this works now - why they provide an option that doesn't work is beyond me!