Error Message: "The File Name is Not Valid or Too Long...."

This is my issue: I download a file to my desktop from a website. I, then,
proceed to name that file using only valid characters. The file name is
usually only 55 to 60 characters long. But when I try to move the file into a
more convenient location (folder) on my hard drive, I receive the following
error message: "The file name is not vaild or too long. Specify a different
file name." I, then, have to proceed to shorten the file name to something
really unrecognizable to me, and only then will the file be accepted into the
destination folder.

I never had this problem before. It only started recently (2009). I've had
Windows XP since 2001.

Why is this happening? Can anyone please help me?
--
Wade Terry