Disc scan results; what do these mean?

General Information
Drive: HP DVD Writer 640c
Firmware: CS30
Selected speed: 8 X
PI errors
Maximum: 6
Average: 1.34
Total: 159
PI failures
Maximum: 0
Average: 0.00
Total: 0
PO failures: 0
Maximum: 8.3 %
Average: 7.16 %
Scanning Statistics
Elapsed time: 1:38
Number of samples: 120
Average scanning interval: 8.00 ECC
Glitches removed: 0

Which part?
It says that you cancelled the scan too early :stuck_out_tongue:

well it says there are 159 pi errors but the disc works fine

Every DVD disc (burnt or pressed) will have PI Errors. No burner or DVD is perfect enough to be written to at 100% accuracy (remember a DVD is written to at the micrometer scale)

There are 3 levels of data security to guard against these errors, Parity Inner (PI) and Pairity Outer (PO)

There is an accepted standard for the maximum number a block on a DVD disc should have, but if your disc (if it is a complete scan) appears to fall within those standards.

PI Failures are usually more of a concern, but again, almost every disc has some (though much less PI Failures should appear than PI Errors)

PO Failures are the major concern, and if you have some on a disc, some drives might have trouble reading it, good drives can sometimes recover the data, which should be reburnt

Recommended limits for a disc are 280.
Posting your entire scan would be a better idea.
Then everyone can comment on your overall results.