SPQuery Error :One or more field types are not installed properly. Go to the list settings page to delete these fields

I kept receiving this error for a list when I was using a SPQuery to fetch items from it.
"One or more field types are not installed properly. Go to the list settings page to delete these fields"
The error came up because one of the fields I was calling was not a column of the list.
I removed it from the CAML query and it worked.
So ,I guess this error crops up when the CAML is not properly formed.
U2U CAML query builder is very useful in debugging such errors.