You probably have to untick the option "Use Fuzzy terminology recognition". It enables the recognition of words that are close in spelling (complete/completely). It is useful for plurals ("device" / "devices").
In Wf 4.4 = Quality Check > Glossaries > an then untick the option.
I just had a porblem with Wordfast which on occasion happened before (no pattern as far as I know):
In a sentence to be translated there is a word marked blue (which, as you know, indicates that it is in the glossary/ies selected) - in my case "completely". I pressed ctrl + alt + down to insert the respective translation from the glossary. The word inserted was "Beschwerde" which is wrong and upon further investigation I realized that the word *completey* isn't in any of my selected glossaries at all.
I have no idea how it got to this point or how to correct it. Have I accidentally changed a setting? Has anybody had any similar experience?