ShinySide
Extreme Android User
Only time I had that problem was with OI File Manager... If you read the Market Description, it explains how to fix it. It's because the version that comes with CM6/7 has the wrong signature.
So I tried the Terminal method. Didnt work. When I typed in the last part it ran then said "Failure" so I went with the alternative which is uninstall TiBu and was successful in updating. Either way Thanks man. I had like 5 updates that wouldnt download and install and it was annoying the hell out of me.