Hello lefkri,
The reason you most likely did not see these errors with the short test, is that the test range differs from that of the long test.
The failing tests are reporting bad sectors on the harddrive. While bad sectors usually do not mean that a drive is "failing" it can cause performance issues and potentially corrupted data.
Below are some clips from the advanced user guides describing the test coverage:
Hi-Low Seek
The Hi-Low Seek test verifies a hard disk drive’s actuator arm can accurately move the read/write heads to specific
locations on the disk media. Fixed disk drive read/write heads are moved from the lowest to the highest sector number
and back. This is repeated 50 times. If the Hi-Low Seek test detects errors with the movement of the drive heads, it will
log a test result of Failed and report additional details in the test log.
Funnel Seek
The Funnel Seek test verifies a drive's actuator arm can accurately move the read/write heads to sector locations in a
funnel fashion across the disk media. It moves the drive read/write heads from the first track (track 0) to the last track,
then from the second track to the second to the last track, then from the third track to the third to the last track, and so
on. If the Funnel Seek test detects errors with the movement of the drive heads, it will log a result of Failed and report
additional details in the test log.
Random Seek
The Random Seek test verifies a drive's actuator arm can accurately move the read/write heads to random locations on
the disk media. It moves the drive read/write heads to random sectors for 300 repetitions. If the Random Seek test detects
errors with the movement of the drive read/write heads, it will log a result of Failed in the test log and report additional
details in the test log.
Linear Verify
Verify tests are similar to seek tests, except that in addition the sector data is read and a CRC checksum is calculated
for the data and compared with the CRC value stored on the media for the sector from which the data was read. The
linear verify test checks all sectors on the disk media in sequence. If errors are detected, the sector number is reported
in the test log.
Note: Any defective sectors should also be flagged by DOS as “bad” in the DOS File Allocation Table (FAT),
assuming the hard disk is formatted in DOS. To see if DOS is aware of defective sectors, run the Surface Scan Hard
Disk function from the Utility menu.