That Harris' polls are generally unreliable, or that the last one was in the 50s?
The former is my opinion based on experience, so you can either take it or leave it. The latter point I read in an article last night (which I am sure to be unable to find now) but give me a few moments and I can probably find it in another location...
The Harris Poll 5/15-21/02
"How would you rate the overall job President George W. Bush is doing as president: excellent, pretty good, only fair, or poor?"
Excellent/ Pretty Good 74%
Only Fair/ Poor 25%
Not Sure/ Refused 1%
1,013 sampled