Most current dive computers call for accuracy of plus or minus 1%. You should be getting accuracy to plus or minus 1 foot at 100 feet (and up to plus or minus 4 feet at 399 ft.)
If whatever you were comparing it too was accurate, your computer is screwed and needs to go back in.
Large scale errors across the board (7 ft off from 33' to 140') in particular are unusual and are more alarming than a small error that becomes progressively larger at depth (1 ft at 50', 2' at 100, 3' at 150 ft, etc. ) The last computer I had that had a large and consistent error died on the next dive.
Deco stops aside, your computer is also figuring your N2 loading for an entire dive either 7 feet too shallow or 7 feet too deep. To deep you could live with, but that much too shallow will get you bent.