If you can't manage in any way to tap on the Welcome application and neither screen protector nor debris under the screen appear to be the cause, as suggested in the article, there's a link for repair at the bottom of that page. Or someone here may have a line on someone reputable.
You could try Maceyr's site, she has some suggestions farther down her page,
here.
Type "palm v" calibrate into yahoo and carefully read some of the results, maybe you'll get a lead. Please understand I can't officially vouch for anything suggested regarding the last two possibilities and only supply them for your reference.
Sorry for your trouble, kitty.
Sincerely
Kevin