datagrid and ProcessKeyPreview()

Windows application C#: I have a datagrid, in the 2nd column the user has to
press the enter key between the contents and once entered the data from the
cursor point till end should move to next line and removing those content
from the first line.

I am able to achive this by overrideing ProcessKeyPReview method but
randomly the contents of the previous lines are displayed in next line not
the removed contents(contents are removed from the first line). This happens
very much randomly can any body let me know why excatly this is happening

Any help will be appreciated