Well I had to migrate custom columns from one SharePoint 2010 environment to another, thanks to the following post, I was able to script it and migrate.
Easy right, not so fast, went to check my columns out and got this great error when accessing site columns under site settings
Field type is not installed properly. Go to the list settings page to delete this field.
Turns out I made a typo and left a column type blank. after scouring the internet, i came across somebody brave enough to delete from the content database.
So I looked in the contenttypes table in the Content DB, found the offending record, deleted it and SharePoint started to work again.
I hope this helps.