HP 30b Bug?

[lrdheat]

I’ve read that there are some bugs on the HP 30b…I wonder if what I have encountered is one of the known bugs…I have 22 pairs of maximum/minimum temperatures entered into the data, all values at least 41. The means and sums and quartiles…all of the statistics are correct. When I go to the Prediction option, pressing = to get best model generates ER x/0 error. This did not happen until I reached the 21st entry, and now, the 22nd entry. Is this a known bug?