Did you also clear your Temp folder?

Word may be creating temp file for the paste transaction. If there
isn't enough space available in your Temp folder then that could cause
the error message you describe.

Delete all temp (*.tmp) files:
- Exit Word and Outlook if you are using it as your email editor and
reboot your computer if you recently experienced a crash
- Go to Start/Find/Files or Folders (or Start/Search then select Files
or Folders)
- Change "Look in" to reflect the drive/folder to the root of your
Local drive.
- In the Named text box, type *.tmp
- Click the "Find Now" command
- Delete the temp  files you find.

*Note that these can be deleted directly from the Find Results.

To group the files for a single deletion:
- Click any file in the list
- Press <Ctrl A> to select all

Should you encounter a "File in use" error, press <Ctrl> and click the
file to deselect it.

As an additional note, the Owner file is another temporary files Word
creates. If you have been experiencing multiple crashes or if Word has
been hanging on you then it is best to search for Owner files
(~$*.do?) and delete those as well. These can cause "file in use" and
"read only" errors.

For more information on this and a full cleanup/maintenance procedure
that should be run periodically, see this article:
http://www.mvps.org/word/FAQs/AppErrors/LockedFiles.htm