2 drives + 2 pcs

I have a Dell desktop 4600 8 years old and a Dell laptop 5150 8years old also.
I have a W.D. external drive -My Book Essentials 1T and it works flawlessly with both pcs.
I have a WD My Book Home 2T which gets an error message that it is having trouble writing to Windows. I can find the back up in My Comp but this errorr message indicates some instability/incompatibility and I don't want to lose data.
Is it possible that the 2 T won't work with a laptop or could it be the age of my machines or still could it be that size of the drive for the 40 gig hard drives each pc has?
Thank you

 

>> It was suggested that if I partitioned the 2T into two partitions it would likely work but I do not know about partition magic etc. I was waiting for a new pc to see if it worked.I asked out of curiosity as I have stowed it away till the new pc becomes a reality.
I know you need exact messages to give exact replies but It said , to the effect, that it has trouble writing to windows.
It does create a backup in My Comp but intermittently gives the same error message.
I think the only way I will really find out is if I get that new pc and try it. WD tech says it is fine.

 

>>Knock on wood but I took the drive out of the box and it appears to be working.
I read about others having trouble at first but then for some unknown reason the drive cooperated. I then formatted, rebooted and put it through a few drills.
I was going to give you the exact error message but it has not appeared to date.
Let's hope this remains the case.
When I get a new pc I hoipe to have esata as this drive has usb, firewire and esata ports. My pc just accomodates usb- but that's ok as long as it works.