Hp Scanjet 3300C: Inclined lines where colours have been changed.

I only have this problem when I use the HP Precision Scan LT program, my scanner works correctly using HP Scanjet Copy.

When I scan colour photographs, some inclined lines appear on the screen. They also appear in the printer's copy. Sometimes they're very near, and sometimes there are big distances between them. Usually this lines have different colours than the original one.

I have downloaded the updated version of the lamp controller:
sj512slp from the HP Web, but I haven't solved the problem.
I have also reinstalled my scan.

I don't know if it's a hardware problem or a software problem. My brother works at HP, he has asked some engineers, but no one knows nothing about it.

I'm sorry very much if this letter it's a little difficult to understand, but I'm from Spain and my english level is not so high.

Thanks.