Without knowing more about the data, I'd suggest two directions for investigation:
If you expect the number of past occurrences of an error to be a good predictor of future occurrences, try using the Forecast Time Series assistant. For example, web server traffic from one day to the next may be fairly predictable on an hour-to-hour basis, so perhaps the number of errors is, as well.
If you expect environmental factors like free disk space or CPU utilization to play a role in the occurrence of the errors, try using the Predict Numeric Fields assistant to build a model that takes those factors, now, and tries to predict the number of errors in, say, an hour.
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