Zebra T402 on Windows XP

We moved our Zebra T402 from a Windows 98 to a Windows XP computer yesterday. After downloading the updated driver from Zebra, we were able to get the printer to print our barcode labels (using barcode 3 of 9). It had printed blank labels to start, but after setting the correct label size, media type, and print method, it seemed to print fine. However, the barcodes won't scan. The barcodes look correct until you look closely at them; it looks as though the "thick" lines are not printing at a uniform width. Has anyone seen this problem before, or know what might be the problem? We moved it back to the 98 computer, and the barcodes print and scan fine.