i also have a 2001fp, surprisingly it came with no dead pixels. Manufacted July 2004. Sorry I couldn't be of help. I think LCD's right now are the luck of the draw, but 4 in a row? that seems suspicious. They could be sending you "refurbished" monitors, rather than a brand new 2001FP. However, you can't "refurbish" an LCD panel. If a pixel is dead, and I mean dead, not stuck or frozen, it cannot be fixed.
( pretty sure anyway.). This doesn't sound good and tell Dell to provide you with a brand new, fresh from the factory one or fully refund your money.