When I paste into my database, the info does not show up
 

I have been working with a large file for months now, and have recently
started having this problem. I typically take info from other files and
copy/paste it into my large file to combine. However, for some reason, when
I paste the info into the cells, it now does not appear. I also tried to
copy some of the text from my file on to a blank worksheet, and it doesn't
show up there either. We switched to Vista from XP recently, I don't know if
that has anything to do with it. Its a large document, about 16,000 rows.
Is there a limit?
Thanks for any help you can offer.
Jennette